25.5 Dispersion: The Rainbow and Prisms

Everyone likes the sight of a rainbow against a dark sky.

White light is broken into colors by a diamond or clear glass.

The colors of the rainbow are the same as those produced by a prism.

There are about six colors in a rainbow--red, orange, yellow, green, blue, and violet.

When we get pure-wavelength light, we see only one of the six colors.
We can sense thousands of other colors in other situations.
White light is a mixture of all visible wavelength.
Sunlight appears to be a bit yellow because of its mixture of wavelengths, but it does contain all visible wavelengths.
White light is spread out according to wavelength in a rainbow.
When there is a process that changes the direction of light in a way that depends on wavelength, dispersion occurs.
A general phenomenon, dispersion can occur for any type of wave and always involves wavelength dependent processes.

The spread of white light into its full spectrum is called dispersion.

The rainbow is a constant distribution of colors according to wavelength.

Refraction is the cause of dispersion.

The Law of Refraction shows that the angle of refraction depends on the index of refraction.
The index of refraction depends on the medium.
It depends on wavelength for a given medium.

Waves can show dispersion.

Water waves can be dispersed according to wavelength.
When the speed of propagation depends on wavelength, dispersion occurs.
In the production of a rainbow, dispersion may require special circumstances.
All frequencies travel at the same speed.

You can easily hear the sound of a vacuum cleaner hose if you listen to it through a long tube.

Dispersion can reveal a lot about what the wave has encountered.
The so-called empty space has been revealed by the dispersion of radiation from outer space.

A sequence of red to violet is created because the index of refraction increases with decreasing wavelength.

Rainbows are created by reflection and refraction.

You can only see a rainbow when you look away from the sun.
Light enters a drop of water and is reflected from the back of the drop, as shown in The light is refracted both as it enters and as it leaves the drop.
The rainbow of colors seen by an observer depends on how the rays are reflected from the water.
The effect can be seen in waterfalls and lawn sprinklers when the background is dark.

Rainbows are created by reflection and refraction.

The back of the water drop has light reflected from it.

As it leaves the drop, the light is dispersed as it enters.

White light used to transmit messages in a fiber is dispersed and eventually overlaps with other messages.

Since a laser produces a nearly pure wavelength, it has an advantage over white light for transmission of information.
The amount of matter they pass through can be determined by the dispersion of waves coming from outer space.
dispersion can be useful or a nuisance depending on the situation.

Light rays are reflected by a lens.

The image changes when you adjust the focal length of the lens, move the object, or move the screen.

A camera's zoom lens is one of the many optical instruments that have lens.

The law of refraction will be used to explore the properties of lens and how they form images.

The shape of the lens makes it possible for all light rays to cross one another at a single point on the opposite side.

An expanded view of the path of one ray through the lens is shown to show how it changes as it leaves the lens.
Since the index of refraction of the lens is greater than that of air, the ray moves towards the perpendicular as it enters and leaves.
Light is bent toward the axis at both surfaces due to the lens's shape.

The focal length of the lens is determined by the distance from the center to the focal point.

An expanded view of the path taken by ray 1 shows the angles of incidence and refraction at both surfaces.

A converging lens is a lens in which light rays that enter it parallel to its axis cross one another at a single point on the opposite side.

The focal point F is where the light rays cross.

The focal length is the distance from the center of the lens to its focal point.

Sunlight can burn paper if it is focused by a magnifying glass.

Light rays from the sun cross at the focal point of the lens.
The rays will cross closer to the lens that is more powerful.

The more powerful a lens is, the greater its effect on light rays.

A strong lens will focus parallel light rays closer to itself and have a smaller focal length than a weak lens.
The light will focus into a spot that is more intense and powerful.

The focal length of the lens must be given in meters.

If the focal length is given in meters, the power of a lens has the unit diopters.

Eyeglasses and contact lens are prescribed in units of diopters.

Suppose you take a magnifying glass out on a sunny day and it concentrates sunlight to a small spot away from the lens.

When the Sun's rays reach Earth, they are nearly parallel.

The power of the lens is inverse of the distance from it to the spot.

The focal length is the distance from the center of the lens to the spot.

To find the power of the lens, we must first convert the focal length to meters and then use the equation for power.

This is a powerful lens.

The power of a lens in diopters is not the same as the power in watt.
The word "power" is used for two completely different things.
If you look at a prescription for eyeglasses, you will see the lens powers.
If you look at the label on the motor, you will see the energy consumption rate.

The axis of the lens has an effect on the rays of light that enter it parallel to it.

The focal point of the diverging lens has been shaped so that all light rays entering it parallel to its axis appear to originate from the same point.
The focal length of the lens is the distance from the center to the focal point.
The focal length and power of a diverging lens are negative.
An expanded view of the path of one ray through the lens is shown in the figure to show how the shape of the lens affects the path of the ray.

Light entering a diverging lens parallel to its axis appears to originate at its focal point.

The dashed lines are not rays.
A diverging lens has a negative focal length.
An expanded view of the path taken by ray 1 shows the angles of incidence and refraction at both surfaces.

A diverging lens is a lens that bends the light rays away from its axis.

The Law of Refraction states that the paths of light rays are reversed.

A small light source, like a light bulb, placed at the focal point of a lens results in parallel rays of light from the other side.

In traffic lights, this technique is used to create a beam of light from a source that emits light in all directions.

The law of refraction is used to trace rays.

Ray tracing helps us understand the action of the lens in a variety of situations, from forming images on film to magnifying small print.
There is a set of simple rules for tracing rays through thin glasses.
An ideal thin lens has two surfaces and is thin enough to assume that light rays bend only once.
A thin symmetrical lens has two focal points, one on either side, and both at the same distance from the lens.

A thin lens is defined as one that has a thickness that allows rays to refract but does not allow properties such as dispersion and aberrations.

Look through your glasses and see if they act like thin lenses.

The focal length on either side of the thin lens is the same.

The light rays through the center of a thin lens are assumed to emerge parallel to their original path, shown as a shaded line.

Ray tracing can be done using paper, pencil, and a straight edge.

The focal point of the lens on the other side is where a ray enters.

A ray passing through the center of a converging or diverging lens does not change direction.

A ray exiting a lens through its focal point is parallel to its axis.

A ray that enters a diverging lens by heading toward the focal point on the opposite side exits parallel to the axis.

The focal point of the lens on the other side is where a ray enters.

The focal point F seems to be where a ray entering a diverging lens comes from.

A ray passing through the center of a converging or diverging lens does not change direction.

A ray exiting a lens through its focal point is parallel to its axis.

A ray that enters a diverging lens by heading toward the focal point on the opposite side exits parallel to the axis.

When a projector casts an image onto a screen, a lens forms an obvious image.

The image is not obvious in some cases.
Ray tracing will be used to show how thin lens form images, and equations will be developed to describe the image formation.

To find the location and size of the image, we trace the path of light rays from one point on the object to the top of the person's head.

The figure shows three rays from the top of an object that can be traced.

One of the first rays enters the lens parallel to its axis and goes through the focal point on the other side.

The second ray does not change direction as it passes through the center of the lens.
The third ray leaves the lens parallel to its axis when it passes through the nearer focal point.
The three rays cross at the same point.
There is an image of the top of the person's head.
The rays that come from the same point on the top of the person's head can be seen in a different way.
A complete image can be formed by the rays from her belt buckle crossing at another common point.
Only two rays are needed to locate the image.
There are simple rules for tracing rays.

The image is formed by a lens.

The three chosen rays follow one of the rules for ray tracing so that their paths are easy to determine.
The point where the rays cross is where the image is located.
A real image that can be projected on a screen is formed.

Light rays from one point on the object cross at the location of the image and can be projected onto a screen, a piece of film, or the retina of an eye.

The figure shows how a real image is projected into the eye.
The image is there if it is projected onto a screen or not.

A real image is an image in which light rays from one point on an object cross at another point and can be projected onto a screen.

Real images can be projected.

The object distance is the distance from the center of a lens to an object.

The symbols and height of the image are given.
Images that appear upright relative to the object have positive heights, while those that are inverted have negative heights.
Ray tracing can help you see how images are formed in a variety of situations.
To get numerical information, we use a pair of equations that are derived from a geometric analysis of ray tracing.

The thin lens equations are applicable to all thin lens and thin mirror situations.

Many features of image formation will be explored in these examples.

The center of the lens has an image distance.

To get an approximate location for the image, use ray tracing.

The location of the image and magnification can be calculated using the thin lens equations.
The thin lens equations produce consistent results.

A light bulb placed 0.750 m from a lens with a 0.500 m focal length produces a real image on a poster board as discussed in the example above.

The image location and size are predicted by Ray tracing.

Similar results should be produced by tracing to scale.

Thin lens equations can be used to get numerical solutions.

The image height is greater than the object height by a factor of 2, and the image is inverted.

It is about -2.
The image is inverted if the minus sign is used.

There is no inverting here.

Since both are known, the thin lens equations can be used to find the magnification.

The magnification is negative when the image is inverted.

Consistency is achieved by the use of thin lens equations.
The most precise results are limited by the accuracy of the information.
Ray tracing is limited by the accuracy with which you can draw, but it is useful both conceptually and visually.

When an object is farther from the lens than its focal length, real images are formed.

Movie projectors, cameras, and the eye are all examples of this.
These are referred to as case 1 images.

A different type of image is formed when a person's face is held close to a lens.

The magnification increases until the image begins to blur, if you slowly pull the magnifier away from the face.
The focal length of the lens is the distance at which the image blurs.
The object must be closer to the lens than the focal length to be a magnifier.
This is a case 2 image.
A case 2 image is formed when there is a positive sign.

There is a case 1 image.

The face is not being photographed because the image is closer to the camera than the focus is.
There are two images in this case 2 image.

ray tracing is used to show how an image is formed when an object is held closer to a lens than its focal length.

The rays coming from a common point on the object continue to differ after passing through the lens, but all seem to originate from a point at the location of the image.

Light rays don't actually pass through space, they appear to originate at a virtual image.

A screen at the location of a virtual image will only receive diffuse light from the object, not focused rays from the lens.
A screen on the opposite side of the lens will receive rays that are diverging, and so no image will be projected on it.
The magnified image can be seen with our eyes because the lens of the eye converges the rays into a real image.

The magnification is positive and greater than 1 because the virtual image is larger than the object.

The location and size of an object held closer to a lens than its focal length is predicted by Ray tracing.

Ray 1 enters parallel to the axis and exits through the focal point on the opposite side, while Ray 2 passes through the center of the lens without changing path.
The two rays on the other side of the lens appear to come from a common point, locating the upright, magnified, virtual image.
There are two images in this case 2 image.

A virtual image is an image on the same side of the lens as an object that cannot be projected on a screen.

We expect to get a case 2 virtual image with a magnification greater than 1.

The magnification equation is used to find the magnification.

We can't find the location of the image using the lens equation because we don't have a value.

Since both are known, the thin lens equation can be used to find the magnification.

The image is upright because of magnification.

The magnification is greater than 1, which means that the image is larger than the object by a factor of 4.
The image distance is negative.
The image is on the same side of the lens as the object.
The image cannot be projected.
Since the image distance is greater than the object distance, the image is farther from the lens.
When using a magnification device, the location of the image is not obvious.
Since the image is larger than the object, you may think it's closer.
The farther away the image is, it's useful to correct farsightedness.

A third type of image is formed by a diverging lens.

Try looking through glasses.

The image is smaller than the object.

The magnification is less than 1.
The image is closer to the object.
A case 3 image is formed by a negative focal length or diverging lens.

A car is seen through a lens.

There are three images in this case 3 image.

The image location and size is predicted by ray tracing.

Ray 1 is bent so that it appears to come from the focal point.
Ray 2 goes through the center of the lens.
The upright image is found by the two rays coming from a common point.
This is a case 3 image, which is smaller than the object and closer to the lens.

An object such as a book page can be held from a focal length of -10.0 cm.

It could be used in eyeglasses to correct nearsightedness.

This example is the same as the preceding one, except that the focal length is negative for a diverging lens.

The method of solution is the same, but the results are different.

Since both are known, the magnification equation can be used to find it.

The image is upright because it is positive.

The magnification is less than 1, which means the image is a little over half the size of the object.
The image is on the same side of the lens as the object.
Since the image distance is smaller than the object distance, the image is closer to the lens.
The location of the image isn't obvious when you look through a lens.
Since the image is smaller than the object, you may think it's farther away.
The closer the image is to the object, the better it is for nearsighted people.

Table 25.3 summarizes the three types of images.

The images are referred to as case 1, 2, and 3.

Virtual images can be either real or virtual images, depending on the case.

Real images can be larger or smaller than the object.
A slide projector forms an image larger than the slide, whereas a camera makes an image smaller than the object being photographed.
Virtual images can't be projected.
Virtual images are larger than the object in case 2.
The virtual image is always smaller than the object.
Virtual images can only be seen and photographed with an additional lens.

The same types of images can be formed by mirrors.

Determine if the lenses are diverging or converging.

Those that are thicker near the edges are diverging and those that are thicker near the center are convergent.
On a bright sunny day, try to focus the sunlight onto a piece of paper by taking the converging lens outside.
Determine the focal lengths.
Depending on the type of lens you have selected, the paper may start to burn.

Look at the situation to see if image formation is involved.

Determine if the thin lens equations or ray tracing are to be used.

Even if ray tracing is not required, a sketch is still useful.

Identifying the unknowns will help determine exactly what needs to be determined in the problem.

List what is given and what can be inferred from the problem.

It's helpful to know if the situation involves a case 1, 2, or 3 image.
These are just names for images, but they have certain characteristics that can be used to solve problems.

The ray tracing rules are listed at the beginning of the section.

The thin lens equations are used in most quantitative problems.

Replacing knowns and solving for unknowns is how these are solved.
Several examples are used as guides.

If your answer is consistent with the type of image, magnification, and so on, you have identified the type of image.

Light rays coming from every part of the object can be used to form the final image.

The entire mirror is needed to form an image.

Half a lens will form the same image as a fainter one.

To find an example of an image formed by a mirror, we have to look as far as the nearest bathroom.

There are images behind the mirror that are the same size as the object.
Mirrors can form a variety of images.
Similar to makeup mirrors, dental mirrors can produce a magnified image.
Security mirrors in shops form smaller images than the object.
We will use the law of reflection to understand how mirrors form images, and we will find that mirror images are similar to those formed by lenses.

Figure 25.40 shows how a mirror forms an image.

Two rays emerge from the same point, hitting the mirror and being reflected into the observer's eye.
Both of the rays get into the eye.
The rays appear to come from a common point behind the mirror.
The law of reflection shows that the image and object are the same distance from the mirror.
Since it cannot be projected, the rays only appear to come from a common point behind the mirror.
If you walk behind the mirror, you can't see the image because the rays don't go there.
In front of the mirror, the rays behave like they came from behind the mirror, so that's where the image is located.

A flat mirror reflects two sets of rays from an object into the eye of an observer.

The reflected rays seem to come from behind the mirror.

The law of reflection states that light strikes the surface.

The mirror does not have a well-defined focal point and the reflected rays do not cross at the same point.
The rays would cross at a single point if the mirror was shaped like a parabola.
The cost of making a parabolic mirror is much higher than the cost of making a spherical mirror.
The focal point at F is the distance from the center of the mirror.
The focal length of a mirror is positive.

The focal length of the mirror is the distance from the center to the focal point.

The mirror has a positive focal length.

A more strongly curved mirror has a shorter focal length.

The light reflected from the mirror seems to come from the point F behind the mirror.

The rays of light reflected from a small spherical mirror seem to come from a well-defined focal point behind the mirror.

The mirrors have a negative focal length.

It's as useful for mirrors as it is for lenses.

The focal point of the mirror on the same side reflects a ray approaching it from the opposite direction.

A ray approaching a mirror that is parallel to it's axis is reflected so that it appears to come from the focal point behind the mirror.

The law of reflection applies when a ray strikes the center of a mirror and leaves as it approaches.

A ray approaching a mirror through a focal point that is parallel to its axis is reflected.

A ray approaching a mirror by heading toward its focal point on the opposite side is reflected on the axis.

ray tracing will be used to show how images are formed by mirrors, and we can use it to get numerical information.

Since we assume each mirror is small, we can use the thin lens equations for mirrors.

That is positive and so that we may expect an image similar to the case 1 real image formed by a converging lens.

A real image can be projected onto a screen.
The magnification is negative because the image is inverted.
This is a picture for mirrors.
The image on the same side of the mirror as the object is different from the case 1 image.

An object is closer to the mirror than it is to its focal length.

The rules in the text are used to trace the rays from a common point.
Ray 1 approaches parallel to the axis, Ray 2 strikes the center of the mirror, and Ray 3 goes through the focal point on the way to the mirror.
All three rays cross at the same point after being reflected.
Only two of the three rays are needed to locate the image and determine its height.

The electric room heaters use a mirror to reflect theIR radiation.

The law of reflection is the same as visible light.

The mirror projects a real image of the coil at a distance.

To find the object distance, we are asked to find the location of the coils.
The focal length of the mirror is determined by the radius of the mirror's curve.
The thin lens equations can be used to solve this problem if the mirror is small.

The object is farther from the mirror than the focal length.

The case 1 image is consistent with the fact that a real image is formed.
In front of the mirror, you will get the most concentrated thermal energy.
It could cause burns, so it's not desirable.
If you want the rays to emerge parallel, you should have the focal point of the mirror.

This is similar to a slide projector.

The image is much farther away if the slide is placed slightly farther away from the projector lens.
The image gets farther away as the object gets closer.
The rays are sent out parallel to one another as the object distance approaches the focal length.

A concentrating collector is a device that concentrates the sunlight onto a blackened pipe that contains a fluid.

This heated fluid is pumped to a heat exchanger, where its heat energy is transferred to another system that is used to generate steam, and so generate electricity through a conventional steam cycle.
The sunlight is focused onto the pipe by cave mirrors.
The mirror has a section of a cylinder in it's shape.
Assume that the mirror is a quarter of a full cylinder.

The fluid is mineral oil and the solar radiation incident is absorbed by the pipe.

Identifying the physical principles involved in an Integrated Concept Problem is the first step.

The current topic is related to part (a).
Part (b) is mostly geometry.
An understanding of heat and density is required.

The focal point of the sun's rays will be an approximation for a semi-spherical surface.

There is an insolation.

Since the power delivered is, we must find the cross-sectional area of the mirror.

The increase in temperature was given by.

On a sunny day in the California desert, an array of such pipes can provide a thermal output of 250 MW, with fluids reaching temperatures as high as.

We are not considering heat losses along the pipe.

In southern California,bolic trough collectors are used to generate electricity.

This is similar to a case 2 image, which is a magnification.

Makeup mirrors act as magnifications.
The image cannot be projected because the rays from a common point on the object appear to be coming from behind the mirror.
The image is larger than the object and upright.
This is a case 2 image for mirrors.

ray 1 approaches parallel to the axis, ray 2 strikes the center of the mirror, and ray 3 approaches the mirror as if it came from the focal point.

The upright virtual image behind the mirror shows the rays to be larger than the object after being reflected.

A negative mirror forms only one type of image.

It is a case 3 image that is upright and smaller than the object.
The image behind the mirror is a virtual image.
It is seen to be smaller than the object.

The images are formed by a mirror.

Ray 1 approaches parallel to the axis, Ray 2 strikes the center of the mirror, and Ray 3 approaches the focal point.
The rays appear to come from the same point after being reflected, with the upright virtual image behind the mirror showing it to be smaller than the object.
Because the image is smaller, a larger area is imaged compared to what would be observed for a flat mirror.

A keratometer is a device used to measure the curve of the eye.

The light reflected from the cornea acts like a mirror and the magnification of the image is measured by the keratometer.

If we can find the focal length of the mirror, we can find its radius, which is twice the focal length of a spherical mirror.

The first thing we do is solve for the image distance.

We take the absolute value to give us a positive value for the focal length of the mirror.

It's reasonable for the radius of curvature to be reasonable.
The eye's distance from the cornea to the retina is about 2.0 cm.
The job of fitting contact lens is complicated by the fact that many corneas are not spherical.
The image distance is negative, which is consistent with the fact that the image is behind the mirror.
You will see that for a fixed object distance, the smaller the radius of curvature, the smaller the magnification.

The three types of images formed by mirrors are exactly the same as the three types of images formed by lenses.

It's easy to focus on only three types of images--concave mirrors andconvex mirrors.

Find a flashlight and look at the mirror.

The first flashlight should be shined onto the second flashlight, which is turned off.
Estimate the length of the mirror.
You can try shining a flashlight on the curved mirror behind the headlights of a car to determine its focal length.

Look at the situation to see if image formation by a mirror is involved.

The strategies used for mirrors are the same as those used for lenses with one qualification.

The index of refraction is the speed of light in the material and the speed of light in the vacuum.

The total internal reflection location is as follows: (1) directly from the source through empty space; (2) through various media; and (3) after being.

If the incident angle in the first medium is greater than the angle of incidence, the Law of Reflection is invoked.

Light diffuses when it reflects from a rough surface.

The Law of Refraction is based on the transmission of light through optical fibers.

The changing of a light's direction when it passes is called changing of a light's direction.

Diamonds sparkle due to total internal reflection and a large index of refraction.

Light rays take different paths.

The image in which light rays from one point on the object actually cross at the location of the image and can be projected onto a screen, a piece of film, or the retina wavelength is called dispersion.

The dispersion of sunlight into a continuous distribution of colors is involved in thin lens equations.

Some optical systems have problems with the distance of the image from the center of the lens.

Light rays entering a converging lens parallel to its axis virtual image is called image formation by lens and is an image that is on the same side of the lens as the object and cannot be projected on a screen.

The focal point is the point at which light rays cross; for a diverging lens, the focal point is the point from which light are diverging.

The image length is half.

The inverse of its focal length is the power of a lens.

A lens that causes the light rays to bend away from its one type of image, namely a virtual image, is a diverging mirror.

Explain the law of reflection and how the diagram shows the path of rays from the feet to the eye.

What is the name of the person who is out of the water?

In this chapter, reflection from a rough surface is described.

Light can be diffused.

Discuss how you can use this effect to estimate the speed of light.

Light will change direction towards or away from a purpose.

A ring is dropped into water.

When submerged, the gemstone becomes invisible.

How can you tell if the image angles are correct?

The most common type of mirage is an illusion that light keeps light from escaping without being put from distant objects is reflected by a pool of water that into the beam.

Where is the light coming from?
Mirages can be seen when there is a hot layer of air near the ground.

Explain how mirages can be formed given that the air's Refractive index is lower at higher temperatures.

It can be argued that a flat piece of glass, such as in a window, is a lens with an infinite focal length.

If the glass is darker on the other side, you can see a reflection.

Most of the light comes from the two mirrors.

You can see the lens from the film with an arrangement of mirrors.

The camera lens can act like a thin back of your head.

Provide a drawing.

Why are diverging mirrors used?

A full-length mirror can show you the direction you're going.

Its size is not dependent on your distance from it.

Two rays are at the same angle.

In Table 25.1 is the speed of light reflector, off which a laser beam is reflected.

The asteroid hit the Moon trip time.

In medieval times, what percent correction is needed.
Take the distance to the Moon into account.

A scuba diver is training in a pool.

A signal can travel through a third if a ray of light passes from one medium to another.

Suppose light travels from water to another substance.

A ray of light, emitted beneath the surface of an Consider sunlight entering the Earth's atmosphere at unknown liquid with air above it, undergoes total sunrise and sunset.

The time the Sun appears to be above the horizon is longer at sunrise and sunset.

You can use this problem to determine the angle of refraction for different models of the atmosphere.
Your instructor may want to show you how the index of refraction varies with air density.

Crown glass is used in an optical fiber.

It may be totally internally reflected at what minimum angle it is.

The substance incident angle can be determined by the index of refraction.

Determine the critical angle of the red.

A projector has a long lens.

There is a light that goes from air to fused quartz.

How far from a piece of paper must you hold a piece of crown glass and father's reading glasses to try to burn a hole in it?

The beam strikes at an angle.

A camera with a 50.0mm focal length lens is being used to take a picture of a person standing close by.

The red experience in taking or posing for photographs is at what angles.

It can be placed from the film at a distance of 33.0mm.

If you have a 50.0mm focal length camera lens, it is 51.0mm away from the film in the camera.

The incident angle is related to the magnification power.

What is the focal length of the glasses?

When you hold your prescription from the magnifier, it's your prescription for new eyeglasses.

If the film in the camera increases in size, how far from the lens must it be?

Show how used to take pictures of mountains.

A person's photograph of the sun and moon has an object in it.

If the sun is cm high, the reflected image of the sun on the film is 0.167.

Combining thin lens equations will show that the magnification for a thin lens is determined by the focal cornea of the contact lens.

The distance between the object and the mirror is equal to the distance behind the mirror.

Some cameras have a mirror instead of a lens.

The law of reflection can be used to prove the focal length.

This is true for a spherical mirror.

If its diameter is small, it will only help because it will spread out the reflected energy.

In the Problem-Solving Strategy for Mirrors, show how you follow the steps projected by the mirror.

A shopper standing 3.0 m from a security that is 1500 W has a magnification of 0.250 and a mirror that sees his image.

A 250-W heat lamp is fixed to the ceiling in a show to show how you follow the steps in the Problem-Solving bathroom.

Strategy for Mirrors will be used if the light burns out.

In order to get a certain intensity projected on the bathroom floor, you have to determine the resistance of each filament.

The ceiling is high.
The problem will need to involve mirrors.
Your instructor may want you to consider the level of complexity in the electrical components.