Saturday
February 13, 2016

# Homework Help: Physics-Light

Posted by Susan on Tuesday, June 3, 2008 at 4:16pm.

Hey everyone, I am re-taking this exam, but have lost my book and can't get my PDF form of it to work. So I am hoping you can help me with the correct answers.
Thank you!
-Susan

2. Which of the following values represents an index of refraction of an actual material?
A. 0
C. 1 / 2
D. 5 / 4

4. If a 72-candela light source is located at a distance of 3 meters from a surface, the illuminance on the surface is
A. 8 lux.
B. 24 lux.
D. 648 lux.

8. The unit for measuring the rate at which light energy is radiated from a source is the
B. lux.
C. lumen.
D. candela.

9. Compared to yellow light, orange light has
A. the same frequency.
B. a faster wave velocity.
C. a longer wavelength.

13. A virtual image produced by a lens is always
A. larger than the object.
B. smaller than the object.
C. located in front of the lens.
D. located in the back of the lens.<my answer>

14. In which of the following materials is the velocity of light greatest?
A. Air
B. Water
C. Crown glass

16. When a simple magnifying glass is used properly, the image will be formed
A. just inside the focal length of the lens.<my answer>
B. about 250 millimeters in front of the lens.
C. at the focal point of the lens.
D. about 500 millimeters behind the lens.

17. When the image of a distant object is brought into focus in front of a person's retina, the defect is called
A. nearsightedness.
C. chromatic aberration.
D. spherical aberration.

18. Reflecting telescopes are popular because they're
A. more powerful than a refracting telescope.<my answer>
B. smaller than a refracting telescope.
C. easier to build than a refracting telescope.
D. more durable than a refracting telescope.

20. Which of the following occurs when light is reflected from a rough or unpolished surface?
A. The original pattern of the light is distorted.
B. The original pattern of the light is preserved.<my answer>
C. The angle of reflection is less than the angle of incidence.
D. The angle of reflection is greater than the angle of incidence.

21. An object is located 51 millimeters from a diverging lens. The object has a height of 13 millimeters and the image height is 3.5 millimeters. How far in front of the lens is the image located?
A. 1.12 millimeters
B. 13.7 millimeters
D. 189 millimeters

23. When a beam of light passes at an oblique angle into a material of lower optical density, the angle of incidence is
A. less than the angle of reflection.<my answer>
B. less than the angle of refraction.
C. greater than the angle of reflection.
D. greater than the angle of refraction.

25. If an object 18 millimeters high is placed 12 millimeters from a diverging lens and the image is formed 4 millimeters in front of the lens, what is the height of the image?
A. 6 millimeters
B. 8 millimeters
C. 14 millimeters
• Physics-Light - drwls, Tuesday, June 3, 2008 at 4:39pm

You should have done better picking answers at random. All of your 13 choices are wrong. Did you get the other 12 right?

You need to spend some time reviewing the subject, otherwise you do not deserve to pass the assignment. Try answering them again and explain the reasons behind your answers, and I will be glad to critique your reasoning.

• Physics-Light - zenobia, Saturday, June 21, 2008 at 6:37pm

if an object 18 millimeters high is placed 12 millimeters from a diverging lens and the image is formed 4 millimeters in front of the lens, what is the height of the image?

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