Question 1

A radio station broadcasts at a frequency of 92.1 MHz. What is the wavelength of the carrier wave? (Assume the speed of light $$c = 3.00 	imes 10^8$ m/s)

Accepted Answer

$$3.26 m$$

Question 2

Which of the following electromagnetic waves has the shortest wavelength?

Accepted Answer

Gamma rays

Question 3

When you blow across the top of a pop bottle, the size of the bottle affects the resonant frequency. What happens to the frequency as the bottle gets smaller?

Accepted Answer

The frequency increases

Question 4

A telescope that focuses light waves is called:

Accepted Answer

A refracting telescope

Question 5

What is the fundamental frequency for an empty pop bottle that has a length of $$0.20 m$$? (Assume sound speed $$v = 343 m/s)$$

Accepted Answer

$$429 Hz$$

Question 6

Why is lightning seen before thunder is heard?

Accepted Answer

Light travels much faster than sound

Question 7

Which of the following best describes the Doppler effect?

Accepted Answer

A change in frequency or wavelength due to the motion of the source or observer

Question 8

Suppose two electromagnetic waves have the same frequency. Which has the longer wavelength?

Accepted Answer

Both have the same wavelength

Question 9

What is the main reason that radio telescopes are much larger than other types of telescopes?

Accepted Answer

Radio waves have much longer wavelengths, requiring larger dishes for good resolution

Question 10

Which of the following is NOT a good place for an observatory?

Accepted Answer

In a city

Question 11

What is refraction of light?

Accepted Answer

The bending of light as it passes from one medium to another

Question 12

Which equation correctly relates the speed $$v$$, wavelength $$\lambda$$, and frequency $$f of a $$wave?

Accepted Answer

$$v = f \lambda$$

Question 13

A student observes that ultraviolet light and microwaves travel through a vacuum at different speeds. Is this correct?

Accepted Answer

No, all electromagnetic waves travel at the same speed in a vacuum

Question 14

Which of the following is the main advantage of a reflecting telescope over a refracting telescope?

Accepted Answer

Reflecting telescopes can be made much larger without distortion

Question 15

What is the purpose of adaptive optics in telescopes?

Accepted Answer

To minimize the distorting effects of atmospheric turbulence for telescopes on the ground

Question 16

Which of the following wavelength regions cannot be studied with telescopes on the ground?

Accepted Answer

X-rays

Question 17

If the frequency of a wave is doubled while its speed remains constant, what happens to its wavelength?

Accepted Answer

The wavelength is halved

Question 18

Which of the following best explains why the sky appears blue during the day?

Accepted Answer

Shorter (blue) wavelengths of sunlight are scattered more than longer (red) wavelengths

Question 19

A lens forms an image of a distant object. If the object is moved closer to the lens, what happens to the image distance?

Accepted Answer

The image distance increases

Question 20

Which of the following is NOT a use of lenses?

Accepted Answer

Radio telescopes

Waves, Sound, and Optics: Study Guide for Physics

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