Doppler Effect: Learn and Test Your Understanding

Question 1

Which of the following best describes the Doppler effect for sound waves?

Accepted Answer

A decrease in frequency as the source moves away from the observer

Answer

An increase in frequency as the source moves towards the observer

Answer

An increase in wavelength as the source moves towards the observer

Answer

A decrease in wavelength as the source moves away from the observer

Question 2

A train whistle emits a sound with a frequency of 1000 Hz. If the train is moving towards a stationary observer at a speed of 30 m/s, what is the observed frequency by the observer?

Accepted Answer

Greater than 1000 Hz

Answer

Less than 1000 Hz

Answer

Equal to 1000 Hz

Answer

Cannot be determined from the given information

Question 3

Which of the following astronomical observations provides concrete evidence for the expansion of the universe?

Accepted Answer

Redshift of distant galaxies

Answer

Blueshift of nearby galaxies

Answer

Gravitational lensing

Answer

Cosmic microwave background radiation

Question 4

What is the quantitative relationship between the velocity of a moving object and the amount of Doppler shift observed?

Accepted Answer

Direct proportion

Answer

Inverse proportion

Answer

Logarithmic proportion

Answer

Square root proportion

Question 5

The Doppler effect occurs when:

Accepted Answer

Either the source or observer is moving.

Answer

The source and observer are moving towards each other.

Answer

The source and observer are moving away from each other.

Answer

Both the source and observer are stationary.

Question 6

The Doppler effect is commonly utilized to determine the:

Accepted Answer

Speed of moving objects

Answer

Direction of moving objects

Answer

Distance to moving objects

Answer

Mass of moving objects

Question 7

The Doppler shift observed in astronomy is mainly attributed to:

Accepted Answer

The motion of stars towards or away from the observer

Answer

The change in wavelength of light as it travels through space

Answer

The expansion of the universe

Answer

The gravitational pull of black holes

Question 8

A police car with its siren on approaches you. What happens to the siren's frequency?

Accepted Answer

Higher for you than for the police officer

Answer

Lower for you than for the police officer

Answer

Same for both you and the police officer

Answer

Unaffected by the car's motion

Question 9

A star moving away from Earth at 100 km/s emits light. What is the approximate percentage change in its wavelength?

Accepted Answer

0.3%

Answer

0.1%

Answer

1%

Answer

3%

Question 10

Which Doppler effect application utilizes reflected waves?

Accepted Answer

Radar

Answer

Astronomy

Answer

Medical imaging

Answer

Weather forecasting

Question 11

The Doppler effect can be used to determine the speed of:

Accepted Answer

Both light and sound

Answer

Light only

Answer

Sound only

Answer

Neither light nor sound

Question 12

Which of the following formulas correctly represents the Doppler effect for a receding light source in astronomy?

Accepted Answer

λ = λ₀ - (v/c)λ₀

Answer

λ = λ₀ + (v/c)λ₀

Answer

f = f₀ - (v/c)f₀

Answer

f = f₀ + (v/c)f₀

Question 13

Which of the following is not a practical application of the Doppler effect?

Accepted Answer

Traffic light timing

Answer

Police radar guns

Answer

Medical ultrasound imaging

Answer

Astronomical spectroscopy

Question 14

When a light source moves away from an observer, what happens to the wavelength of the light?

Accepted Answer

It decreases (redshift).

Answer

It increases (blueshift).

Answer

It remains the same.

Answer

It becomes infinite.

Question 15

What is the key difference between a longitudinal wave and a transverse wave?

Accepted Answer

Longitudinal waves oscillate parallel to the direction of propagation, while transverse waves oscillate perpendicular to the direction of propagation.

Answer

Longitudinal waves have a higher frequency than transverse waves.

Answer

Longitudinal waves have a lower wavelength than transverse waves.

Answer

Transverse waves have a higher speed than longitudinal waves.

Question 16

Which of the following accurately describes the Doppler effect?

Accepted Answer

It is the change in the frequency and wavelength of waves due to the movement of the source or observer.

Answer

It occurs exclusively when sound waves are emitted by a moving object.

Answer

It only affects the amplitude of waves.

Answer

It is a phenomenon that is rarely encountered in everyday situations.

Question 17

How does the speed of a moving source relate to the observed change in frequency?

Accepted Answer

The change in frequency is directly proportional to the source's speed.

Answer

The change in frequency is inversely proportional to the source's speed.

Answer

The change in frequency is independent of the source's speed.

Answer

The change in frequency is inversely proportional to the square of the source's speed.

Question 18

Which of the following applications of the Doppler effect is used in the field of astronomy?

Accepted Answer

Measuring the speed of stars and galaxies

Answer

Detecting hidden objects

Answer

Improving the quality of medical images

Answer

Monitoring traffic flow

Question 19

As an ambulance with its siren on approaches you, what change in sound will you perceive?

Accepted Answer

Higher pitch, shorter wavelength

Answer

Higher pitch, longer wavelength

Answer

Lower pitch, shorter wavelength

Answer

Lower pitch, longer wavelength

Question 20

If an observer moves towards a light source, how will the observed frequency change?

Accepted Answer

Increase (blue shift)

Answer

Decrease (red shift)

Answer

Remain the same

Answer

Reverse direction

Question 21

What is the primary cause of the Doppler effect in sound waves?

Accepted Answer

Compression and expansion of the medium due to the source's or observer's motion

Answer

Reflection of sound waves off a moving surface

Answer

Change in the speed of sound with temperature

Answer

Interference of sound waves from multiple sources

Question 22

Which application of the Doppler effect involves measuring the velocity of moving objects?

Accepted Answer

Doppler radar

Answer

Astronomy

Answer

Medical imaging

Answer

Sonography

Question 23

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

Accepted Answer

Temperature of the medium

Answer

Speed of the source or observer

Answer

Velocity of the wave

Answer

Direction of motion

Question 24

A train's whistle emits a frequency of 500 Hz. If the train approaches a stationary observer at a speed of 20 m/s and the speed of sound is 340 m/s, what frequency will the observer perceive?

Accepted Answer

524 Hz

Answer

476 Hz

Answer

600 Hz

Answer

680 Hz

Question 25

Describe 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 26

To which type of wave does the Doppler effect NOT apply?

Accepted Answer

Gravitational waves

Answer

Sound waves

Answer

Light waves

Answer

Water waves

Question 27

When a source moves towards an observer and then away from the observer, what is the difference in the Doppler shift?

Accepted Answer

The frequency increases when the source moves towards the observer and decreases when it moves away.

Answer

The frequency increases in both cases.

Answer

The frequency decreases in both cases.

Answer

The frequency decreases when the source moves towards the observer and increases when it moves away.

Question 28

As a train approaches, its whistle is perceived at a higher pitch, and as it recedes, it is perceived at a lower pitch. What type of Doppler Effect is this?

Accepted Answer

Blueshift

Answer

Redshift

Answer

Gravitational redshift

Answer

Time dilation

Question 29

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

Accepted Answer

Temperature of the medium

Answer

Relative speed between the source and observer

Answer

Original wave frequency

Answer

Direction of the source's motion

Question 30

The redshift observed in light from distant galaxies is an illustration of:

Accepted Answer

Redshift due to recession

Answer

Gravitational redshift

Answer

Blueshift due to approach

Answer

Time dilation

Question 31

The Doppler Effect is also referred to as the:

Accepted Answer

Doppler-Fizeau effect

Answer

Einstein effect

Answer

Michelson-Morley effect

Answer

Lorentz-FitzGerald effect

Question 32

Which of the following is an application of the Doppler effect in astronomy?

Accepted Answer

Estimating the speed of distant stars

Answer

Measuring the distance to nearby stars

Answer

Detecting hidden objects on Earth

Answer

Monitoring weather patterns

Question 33

A bat emits sound waves with a frequency of 100 kHz. What frequency will the bat hear when the sound waves reflect off a wall moving towards it at 10 m/s?

Accepted Answer

105 kHz

Answer

95 kHz

Answer

100 kHz

Answer

110 kHz

Question 34

Which of the following factors does NOT affect the Doppler effect?

Accepted Answer

Amplitude of the wave

Answer

Speed of the source

Answer

Speed of the observer

Answer

Wavelength of the wave

Question 35

Which of the following is an application of the Doppler effect in medicine?

Accepted Answer

Ultrasound imaging

Answer

Radar speed detection

Answer

Astronomy

Answer

Earthquake detection

Question 36

Which of the following is the SI unit of frequency?

Accepted Answer

Hertz (Hz)

Answer

Meter per second (m/s)

Answer

Joule (J)

Answer

Newton (N)

Question 37

Which of the following is an example of the Doppler effect in everyday life?

Accepted Answer

The change in pitch of a car horn as it passes by

Answer

The change in color of a traffic light as you approach it

Answer

The change in the speed of a bullet as it flies through the air

Answer

The change in the direction of a wave as it passes through a different medium

Question 38

Which of the following is NOT a practical application of the Doppler effect?

Accepted Answer

Tuning musical instruments

Answer

Measuring the speed of moving objects

Answer

Medical imaging (e.g., ultrasound)

Answer

Weather forecasting (e.g., Doppler radar)

Question 39

A stationary observer faces a moving sound source. The sound's observed frequency is higher than its emitted frequency. What is the direction of the source's motion?

Accepted Answer

Towards the observer

Answer

Away from the observer

Answer

Left to right

Answer

Right to left

Question 40

Besides sound waves, the Doppler effect is applicable to other wave types. Which of the following is NOT a wave that exhibits the Doppler effect?

Accepted Answer

Magnetic waves

Answer

Light waves

Answer

Water waves

Answer

Radio waves