Question 1

Which type of electromagnetic wave has the shortest wavelength and highest frequency?

Accepted Answer

Gamma rays

Question 2

According to the equation $$ \lambda = \frac{c}{f} $$, what happens to the wavelength $$ \lambda  if $$the frequency $$ f $$ increases, assuming the speed of light $$ c  is $$constant?

Accepted Answer

Wavelength decreases

Question 3

Snell's Law is given by $$ n_1$ \sin \$$theta_1$$ = n_2$ \sin \$$theta_2$$ . If $$light passes from air ($$ n_1$ = 1.0 ) $$into water ($$ n_2$ = 1.33 ) at an $$angle of $$ 30^	ext{o}  to $$the normal, what is the angle of refraction $$ \$$theta_2$$  in $$water?

Accepted Answer

$$ \$$theta_2$$ \approx 22^	ext{o} $$

Question 4

If the speed of light in a medium is $$ 2.0 	imes 10^8$  m/s$$, what is the refractive index of the medium?

Accepted Answer

$$ n = 1.5 $$

Question 5

A ray of light strikes a mirror at an angle of $$ 40^	ext{o}  to $$the normal. What is the angle between the incident ray and the reflected ray?

Accepted Answer

$$ 80^	ext{o} $$

Question 6

A converging lens has a focal length of $$ 10  cm. An $$object is placed $$ 30  cm $$from the lens. Using the lens equation $$ \frac{1}{f} = \frac{1}{d_o} + \frac{1}{d_i} $$, what is the image distance $$ d_i $$?

Accepted Answer

$$ d_i = 15  cm$$

Question 7

If an object is placed at a distance less than the focal length of a convex lens, what type of image is formed?

Accepted Answer

Virtual and upright

Question 8

A concave mirror has a focal length of $$ 20  cm. An $$object is placed $$ 60  cm $$from the mirror. What is the magnification of the image?

Accepted Answer

$$ m = -0.33 $$

Question 9

Which statement about critical angle is correct?

Accepted Answer

It is the angle of incidence at which light is totally reflected within a denser medium.

Question 10

A person looks at a fish underwater. The fish appears closer to the surface than it actually is. This phenomenon is due to:

Accepted Answer

Refraction

Question 11

The power of a lens is given by $$ P = \frac{1}{f}  (in $$diopters). What is the power of a lens with focal length $$ 0.5  m$$?

Accepted Answer

$$ 2  D$$

Question 12

Which optical instrument uses a converging lens to form a real, inverted image that is magnified?

Accepted Answer

Camera

Question 13

If the object distance $$ d_o  is$$ $$ 25  cm $$and the image distance $$ d_i  is$$ $$ -50  cm $$for a lens, what is the focal length $$ f $$?

Accepted Answer

$$ f = -16.7  cm$$

Question 14

Which of the following best describes the image formed by a diverging lens?

Accepted Answer

Virtual, upright, and reduced

Question 15

A ray of light passes from glass ($$ n = 1.5 ) $$into air ($$ n = 1.0 ) at an $$angle greater than the critical angle. What happens?

Accepted Answer

The ray is totally internally reflected.

Question 16

Which of the following is true about the focal length of a convex mirror?

Accepted Answer

It is negative.

Question 17

A microscope uses two lenses: the objective and the eyepiece. If the objective has a focal length of $$ 2  cm $$and the eyepiece has a focal length of $$ 5  cm$$, which combination will result in higher magnification?

Accepted Answer

Shorter focal length for both lenses

Question 18

Which statement about the law of reflection is correct?

Accepted Answer

The angle of incidence is equal to the angle of reflection.

Question 19

A hypermetropic (farsighted) person uses a lens of power $$ +2  D. $$What is the focal length of the lens?

Accepted Answer

$$ 0.5  m$$

Question 20

Which of the following is a real-world application of total internal reflection?

Accepted Answer

Optical fiber communication

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