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PLEASE FOR POINTS: I need help with explanations, etc. if you would like full po

ID: 1312474 • Letter: P

Question

PLEASE FOR POINTS: I need help with explanations, etc. if you would like full points. I appreciate the help, I am working on them, but always feel safer with a second opinion on my results. I'll edit as I go along, and if I have one wrong, please explain why. Thanks!

[1] If a lens is submerged in water, its focal length

A) decreases. B) becomes negative. C) stays the same. D) decreases.

[2] Which of the following is true?

A) A concave mirror always produces a real image.

B) A convex mirror always produces a real image.

C) A concave mirror always produces a virtual image.

D) A convex mirror always produces a virtual image.

[3] A light ray incident at an interface between two materials is totally internally

reflected. This requires that the incident ray

(a) comes from the material with the greater index of refraction.

(b) comes from the material with the lower index of refraction.

(c) may come from either side, depending on the angle of incidence.

(d) is absorbed by the second material.

(e) is perpendicular to the interface.

[4] Geologist Rok Ahn examines a rock using a magnifying lens. She holds the rock very

close to the lens and looks through it to see a magnified image which is upright. Which of

the following describes most likely image and lens combination?

(A) A virtual image formed by a concave lens.

(B) A real image formed by a concave lens.

(C) A virtual image formed by a convex lens.

(D) A real image formed by a convex lens.

(E) impossible to determine.


[5] Holding a 5 cm diameter lens up between a light and the wall, you

notice that the pattern on the wall consists of a bright center spot

with a region of reduced light intensity around it and normal light

intensity outside that. The lens must

(a) have a negative focal length. (b) be very small.

(c) be convex. (d) be dirty around the edges.

[6] A curved mirror produces a real image. If the light is from the left, the image is

located

(a) left of the mirror. (b) at the mirror surface.

(c) right of the mirror. (d) only in your mind.

[7] The image on a screen from a projector is

(a) real (b) virtual (c) imaginary (d) only a product of your brain.

[8] In the side view mirror on the Landrover at

Jurassic Park the passengers see a view of a

T Rex only a dentist could love. The objects in

the very wide view are reduced in size and a

notice at the bottom states that

Explanation / Answer

[1] If a lens is submerged in water, its focal length

Ans:[D] When immersed in water, the difference between light's speed in the lens and the surrounding medium is less than the difference when it's in air, and the focal length of a lens would be greater under water.

[2] Which of the following is true?

Ans:[D]Concave mirror produce real image when the object is placed between focus and infinity then and virtual when it is placed between focus and pole and convex mirror always produce virtual image.

[3] A light ray incident at an interface between two materials is totally internally reflected. This requires that the incident ray

Ans: (a) comes from the material with the greater index of refraction.

sintheta=n2/n1 and n2/n1 must be lass than 1. So, n1>n2

[4] Geologist Rok Ahn examines a rock using a magnifying lens. She holds the rock very close to the lens and looks through it to see a magnified image which is upright. Which of the following describes most likely image and lens combination?

Ans:(A) A virtual image formed by a concave lens.

[5] Holding a 5 cm diameter lens up between a light and the wall, you notice that the pattern on the wall consists of a bright center spot with a region of reduced light intensity around it and normal light intensity outside that. The lens must

Ans: (a) have a negative focal length.

[6] A curved mirror produces a real image. If the light is from the left, the image is located

Ans:(a) left of the mirror

[7] The image on a screen from a projector is

Ans:(b) virtual

[8] In the side view mirror on the Landrover at Jurassic Park the passengers see a view of a T Rex only a dentist could love. The objects in the very wide view are reduced in size and a notice at the bottom states that

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