Tactics Box 18.2 Ray Tracing for a Converging Lens Learning Goal: To practice Ta

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Tactics Box 18.2 Ray Tracing for a Converging Lens

Learning Goal:

To practice Tactics Box 18.2 Ray tracing for a converging lens.

The procedure known as ray tracing is a pictorial method for understanding image formation when lenses or mirrors are used. It consists in locating the image by the use of just three "special rays" The following Tactics Box explains this procedure for the case of a converging lens.

Part B

Now draw the refracted segments of the three special rays considered previously. Use the labels Ray1r, Ray2r, Ray3r for the refracted segment of Ray 1, the refracted segment of Ray 2, and the refracted segment of Ray 3. Make certain to extend the refracted rays until they all converge. If your rays do not all converge in the same point, you may need to be more precise in using the drawing tool.

Draw the vectors for the refracted rays starting from the point where the incident ray hits the converging lens.The location and orientation of the vectors will be graded.The length of the vectors will not be graded.

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Problem 18.32 - Enhanced - with Feedback

Part A

Calculate the image position.

Express your answer to two significant figures and include the appropriate units.

Problem 18.34 - Enhanced - with Feedback

Part A

Calculate the image position.

Express your answer to two significant figures and include the appropriate units.

-13 cm

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Correct

Here we learn how to determine the image position using the thin-lens equation.

Part B

Calculate the image height. Type a positive value if the image is upright and a negative value if it is inverted.

Express your answer to two significant figures and include the appropriate units.

Problem 18.72

The moon is 3.5 × 106 m in diameter and 3.8× 108 m from the earth's surface.
The 1.1-m-focal-length concave mirror of a telescope focuses an image of the moon onto a detector.

Part A

What is the diameter of the moon's image?

Express your answer to two significant figures and include the appropriate units.

Problem 18.76

A slide projector needs to create a 94-cm-highimage of a 2.0-cm-tall slide. The screen is 300 cm from the slide.

Part A

What focal length does the lens need? Assume that it is a thin lens.

Express your answer to two significant figures and include the appropriate units.

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Part B

How far should you place the lens from the slide?

Express your answer to two significant figures and include the appropriate units.

Problem 18.77

The writing on the passenger-side mirror of your car says "Warning! Objects in mirror are closer than they appear" (Figure 1) . There is no such warning on the driver's mirror. Consider a typical convex passenger-side mirror with a focal length of -80 cm. A 1.5-m-tall cyclist on a bicycle is 21 m from the mirror. You are 1.0 m from the mirror, and suppose, for simplicity, that the mirror, you, and the cyclist all lie along a line.

Part A

How far are you from the image of the cyclist?

Express your answer to two significant figures and include the appropriate units.

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Incorrect; Try Again; 5 attempts remaining

Part B

How far would you have been from the image if the mirror were flat?

Express your answer to two significant figures and include the appropriate units.

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Incorrect; Try Again; 5 attempts remaining

Part C

What is the image height?

Express your answer to two significant figures and include the appropriate units.

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Part D

What would the image height have been if the mirror were flat?

Express your answer to two significant figures and include the appropriate units.

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Part E

Why is there a warning label on the passenger-side mirror?

Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

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smaller

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The mirror at the passenger's side is often convex to make the viewing angle

The image is than the object and so the driver might think that the object is at greater distance than it is in reality, so if driver stop suddenly thinking the cyclist will have time to stop also, he might be unpleasantly surprised.

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Figure 1 of 1

Tactics Box 18.2 Ray Tracing for a Converging Lens

Learning Goal:

To practice Tactics Box 18.2 Ray tracing for a converging lens.

The procedure known as ray tracing is a pictorial method for understanding image formation when lenses or mirrors are used. It consists in locating the image by the use of just three "special rays" The following Tactics Box explains this procedure for the case of a converging lens.

Part B

Now draw the refracted segments of the three special rays considered previously. Use the labels Ray1r, Ray2r, Ray3r for the refracted segment of Ray 1, the refracted segment of Ray 2, and the refracted segment of Ray 3. Make certain to extend the refracted rays until they all converge. If your rays do not all converge in the same point, you may need to be more precise in using the drawing tool.

Draw the vectors for the refracted rays starting from the point where the incident ray hits the converging lens.The location and orientation of the vectors will be graded.The length of the vectors will not be graded.

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Explanation / Answer

18.76)

Magnification, m = ho/hi = 94/2 = 46

v/u = 46

v = 46u ........(1)

v + u = 300

u = (300 - v) ---- substitute into (1)

v = 46(300 - v)

47v = 13800

v = 293.6 cm, therefore u = 6.4 cm

a)

1/f = 1/u + 1/v

1/f = 1/6.4 + 1/293.6

1/f = 0.1597

f = + 6.26 cm (0.0626m)

b)

Object (slide) distance = u = 6.4 cm (0.064 m)

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