Doppler Effect: Understanding the Change in Wave Frequency

Question 1

Which of the following is a practical application of the Doppler effect for light waves?

Accepted Answer

Measuring the speed of stars

Answer

Detecting hidden objects behind walls

Answer

Determining the direction of a moving object

Answer

Enhancing the resolution of images

Question 2

Which factor does NOT influence the Doppler effect?

Accepted Answer

Temperature of the source

Answer

Motion of the source

Answer

Motion of the observer

Answer

Nature of the waves

Question 3

Which example illustrates the transverse Doppler effect?

Accepted Answer

Change in color of light emitted by a moving star

Answer

Alteration in pitch of a siren as it approaches

Answer

Variation in frequency of sound waves reflected from a moving surface

Answer

Change in speed of sound waves propagating in a moving medium

Question 4

What is the basis for utilizing the Doppler effect in medical diagnostics?

Accepted Answer

Detecting blood flow movement

Answer

Producing high-resolution images of organs

Answer

Estimating tumor dimensions

Answer

Assessing tissue metabolism

Question 5

Which real-world phenomenon exemplifies the Doppler effect for light waves?

Accepted Answer

Redshift of light from distant galaxies

Answer

Changing color of a traffic light as you approach

Answer

Reflection of light from a moving mirror

Answer

Refraction of light through a prism

Question 6

Which of the following is NOT an application of the Doppler effect in everyday life?

Accepted Answer

Remote controls for televisions

Answer

Speeding radar guns

Answer

Weather radar

Answer

Ultrasound imaging in medicine

Question 7

When a source of sound moves towards a stationary observer, what happens to the observed frequency?

Accepted Answer

Increases

Answer

Decreases

Answer

Remains the same

Answer

Becomes zero

Question 8

Which of the following applications of the Doppler effect is used in medical imaging?

Accepted Answer

Ultrasound scans

Answer

Radar speed detectors

Answer

Weather forecasting

Answer

Astronomy

Question 9

What is the relationship between the Doppler shift and the velocity of the source?

Accepted Answer

Directly proportional

Answer

Inversely proportional

Answer

Logarithmically proportional

Answer

No relationship

Question 10

Which statement accurately describes the Doppler effect for sound waves?

Accepted Answer

The change in frequency of sound waves as the source or observer moves relative to each other

Answer

The change in speed of sound as the source or observer moves relative to each other

Answer

The change in amplitude of sound waves as the source or observer moves relative to each other

Answer

The change in wavelength of sound waves as the source or observer moves relative to each other

Question 11

A train whistle has a frequency of 400 Hz. What is the frequency of the whistle heard by an observer standing on the platform as the train approaches at 20 m/s (speed of sound = 340 m/s)?

Accepted Answer

424 Hz

Answer

400 Hz

Answer

376 Hz

Answer

348 Hz

Question 12

A radar emits microwaves with a frequency of 10 GHz. What is the wavelength of the microwaves detected by a car moving at 30 m/s towards the radar (speed of light = 3 x 10^8 m/s)?

Accepted Answer

0.029 m

Answer

0.03 m

Answer

0.027 m

Answer

0.025 m

Question 13

Which statement about the Doppler effect for sound waves is correct?

Accepted Answer

The frequency of the sound wave increases as the source approaches the observer.

Answer

The frequency of the sound wave decreases as the source approaches the observer.

Answer

The wavelength of the sound wave increases as the source approaches the observer.

Answer

The wavelength of the sound wave decreases as the source approaches the observer.

Question 14

The Doppler effect can be applied to determine the velocity of a moving object by analyzing the shift in frequency or wavelength of the waves emitted by the object.

Accepted Answer

True

Answer

False

Question 15

The Doppler effect arises due to:

Accepted Answer

Variations in the velocity of the source or observer

Answer

Changes in the distance between the source and observer

Answer

Alterations in the direction of the source or observer

Answer

Modifications in the medium through which the waves propagate

Question 16

Which factor does NOT influence the magnitude of the Doppler effect?

Accepted Answer

Density of the medium through which the waves travel

Answer

Velocity of the source or observer

Answer

Frequency of the emitted waves

Answer

Angle between the direction of motion and the direction of wave propagation

Question 17

Radar guns utilize the Doppler effect to measure the velocity of moving vehicles. What is the underlying principle behind this application?

Accepted Answer

Changes in the frequency of radar waves reflected from the vehicle

Answer

Alterations in the phase of radar waves reflected from the vehicle

Answer

Variations in the amplitude of radar waves reflected from the vehicle

Answer

Modifications in the polarization of radar waves reflected from the vehicle

Question 18

The Doppler effect can be used to determine which of the following quantities for moving objects?

Accepted Answer

Both speed and direction

Answer

Speed

Answer

Direction

Answer

Neither speed nor direction

Question 19

A car horn emitting a sound of 400 Hz approaches a stationary observer at a speed of 20 m/s. The speed of sound in air is 340 m/s. What is the observed frequency?

Accepted Answer

420 Hz

Answer

380 Hz

Answer

400 Hz

Answer

440 Hz

Question 20

When a light source moves towards a stationary observer, the observed wavelength:

Accepted Answer

Decreases (blueshift)

Answer

Increases (redshift)

Answer

Remains the same

Answer

Becomes infinite

Question 21

The redshift observed in light from distant galaxies is primarily due to:

Accepted Answer

Expansion of the universe

Answer

Gravitational effects

Answer

Atmospheric absorption

Answer

Doppler shift caused by the Earth's rotation

Question 22

In which of the following situations will the observed frequency be the **highest**?

Accepted Answer

An observer moving towards a stationary source

Answer

A source moving away from a stationary observer

Answer

A source moving towards a moving observer

Answer

A source stationary relative to an observer

Question 23

Which of the following does NOT affect the magnitude of the Doppler shift?

Accepted Answer

Polarization of the waves

Answer

Speed of the moving object

Answer

Frequency of the waves

Answer

Direction of wave propagation

Question 24

The Doppler effect is a consequence of:

Accepted Answer

Wave superposition and interference

Answer

Wave interference

Answer

Wave diffraction

Answer

Wave reflection

Question 25

The redshift in the spectrum of light from distant galaxies indicates that they are:

Accepted Answer

Moving away from us

Answer

Moving towards us

Answer

Stationary relative to us

Answer

Rotating around their own axis

Question 26

Which of the following does NOT affect the magnitude of the Doppler effect for sound waves?

Accepted Answer

Temperature of the medium

Answer

Speed of the source or observer

Answer

Frequency of the source

Answer

Direction of the motion

Question 27

The Doppler effect is NOT observed when the source and observer are:

Accepted Answer

Moving at the same speed

Answer

Moving towards each other

Answer

Moving away from each other

Answer

Moving perpendicular to each other

Question 28

In astronomy, the Doppler effect for light is utilized to determine the:

Accepted Answer

Redshift of distant galaxies

Answer

Temperature of stars

Answer

Distances to planets

Answer

Chemical composition of nebulae

Question 29

A police radar emits microwaves at 24 GHz toward a moving vehicle. The vehicle's speed can be calculated by measuring the:

Accepted Answer

Difference in frequency between the transmitted and reflected waves

Answer

Amplitude of the reflected waves

Answer

Phase shift of the reflected waves

Answer

Wavelength of the reflected waves

Question 30

When a light source moves perpendicularly to an observer, the observed wavelength will:

Accepted Answer

Remain constant

Answer

Increase

Answer

Decrease

Answer

Become zero

Question 31

Which of the following is not a limitation of using the Doppler effect to measure speed?

Accepted Answer

Unaffected by atmospheric conditions

Answer

Ineffectiveness for objects with low speeds

Answer

Inability to discern the direction of motion

Answer

Requirement for a clear line of sight

Question 32

When a source of sound is moving towards a stationary observer, the observed frequency will be:

Accepted Answer

Higher than the emitted frequency

Answer

Lower than the emitted frequency

Answer

Equal to the emitted frequency

Answer

Zero

Question 33

Which of the following is NOT a characteristic of the Doppler effect?

Accepted Answer

Change in amplitude

Answer

Change in frequency

Answer

Change in wavelength

Answer

Change in velocity of the source or observer

Question 34

A car moving towards a stationary observer will produce a sound with a:

Accepted Answer

Higher frequency and shorter wavelength

Answer

Higher frequency and longer wavelength

Answer

Lower frequency and shorter wavelength

Answer

Lower frequency and longer wavelength

Question 35

The Doppler effect can be used to determine:

Accepted Answer

Both the velocity of the source and the observer

Answer

Only the velocity of the source

Answer

Only the velocity of the observer

Answer

Neither the velocity of the source nor the observer

Question 36

Which of the following factors does NOT affect the magnitude of the Doppler shift?

Accepted Answer

Angle between the direction of motion and the observer

Answer

Relative velocity between source and observer

Answer

Frequency of the emitted wave

Answer

Speed of sound or light in the medium

Question 37

The Doppler effect is:

Accepted Answer

Applicable to both sound and electromagnetic waves

Answer

Only applicable to sound waves

Answer

Only applicable to electromagnetic waves

Answer

Not applicable to any type of wave

Question 38

A medical ultrasound machine uses the Doppler effect to:

Accepted Answer

Measure blood flow velocity

Answer

Generate images of internal organs

Answer

Detect tumors

Answer

Diagnose heart conditions

Question 39

Which of the following is NOT a characteristic of the Doppler effect?

Accepted Answer

It is only applicable to sound waves

Answer

It occurs when the source or observer is moving relative to the medium

Answer

It can be used to measure velocity

Answer

It results in a change in frequency or wavelength

Question 40

The redshift of light from distant galaxies provides evidence for:

Accepted Answer

The expansion of the universe

Answer

The contraction of the universe

Answer

The rotation of the Earth

Answer

The motion of stars within galaxies

Question 41

A car approaches a stationary observer while sounding its horn. The observer will hear a sound:

Accepted Answer

with a higher frequency than that emitted by the car.

Answer

with a lower frequency than that emitted by the car.

Answer

with the same frequency as that emitted by the car.

Answer

that is not affected by the motion of the car.

Question 42

In a longitudinal wave, particle displacement occurs:

Accepted Answer

parallel to the wave's direction of travel.

Answer

perpendicular to the wave's direction of travel.

Answer

at a 45-degree angle to the wave's direction of travel.

Answer

randomly and unpredictably.

Question 43

As the frequency of a wave increases, its wavelength:

Accepted Answer

decreases.

Answer

increases.

Answer

remains the same.

Answer

cannot be determined without additional information.

Question 44

Which factor does NOT influence the magnitude of the Doppler effect?

Accepted Answer

Polarization of the waves.

Answer

Relative velocity between source and observer.

Answer

Wavelength of the waves.

Answer

Angle between direction of motion and line of sight.

Question 45

Which of the following factors has no influence on the Doppler effect?

Accepted Answer

The amplitude of the emitted wave

Answer

The relative velocity between the source and observer

Answer

The frequency of the emitted wave

Answer

The medium through which the wave is propagating

Question 46

Which of the following is not an instance of a Doppler shift?

Accepted Answer

The change in the speed of sound as it travels through different media

Answer

The change in sound pitch as a car passes by

Answer

The change in colour of a star as it moves away from us

Answer

The change in frequency of a siren as an emergency vehicle approaches