Doppler Effect
WAVES

173020 A man is standing on the platform and one train is approaching and another train is going away with speed of $4 \mathrm{~m} / \mathrm{s}$, frequency of sound produced by train is $240 \mathrm{~Hz}$. What will be the no. of beats heard by him per second?

1 12
2 Zero
3 6
4 3
WAVES

173021 A source of sound of frequency $500 \mathrm{~Hz}$ is moving towards a stationary observer with velocity $30 \mathrm{~m} / \mathrm{s}$. The speed of sound is $330 \mathrm{~m} / \mathrm{s}$. The frequency heard by the observer will be :

1 $545 \mathrm{~Hz}$
2 $580 \mathrm{~Hz}$
3 $458.3 \mathrm{~Hz}$
4 $550 \mathrm{~Hz}$
WAVES

173022 A police car horn emits a sound at a frequency $240 \mathrm{~Hz}$ when the car is at rest. If the speed of sound is $330 \mathrm{~m} / \mathrm{s}$, the frequency heard by an observer who is approaching the car at a speed of $11 \mathrm{~m} / \mathrm{s}$, is :

1 $248 \mathrm{~Hz}$
2 $244 \mathrm{~Hz}$
3 $240 \mathrm{~Hz}$
4 $230 \mathrm{~Hz}$
WAVES

173030 A star is moving towards the earth with a speed of $4.5 \times 10^{6} \mathrm{~m} / \mathrm{s}$. If the true wavelength of a certain line in the spectrum received from the star is $5890 \AA$, its apparent wavelength will be about $\left[\mathrm{c}=\mathbf{3} \times 10^{8} \mathrm{~m} / \mathrm{s}\right]$

1 $5890 \AA$
2 $5978 \AA$
3 $5802 \AA$
4 $5896 \AA$
WAVES

173020 A man is standing on the platform and one train is approaching and another train is going away with speed of $4 \mathrm{~m} / \mathrm{s}$, frequency of sound produced by train is $240 \mathrm{~Hz}$. What will be the no. of beats heard by him per second?

1 12
2 Zero
3 6
4 3
WAVES

173021 A source of sound of frequency $500 \mathrm{~Hz}$ is moving towards a stationary observer with velocity $30 \mathrm{~m} / \mathrm{s}$. The speed of sound is $330 \mathrm{~m} / \mathrm{s}$. The frequency heard by the observer will be :

1 $545 \mathrm{~Hz}$
2 $580 \mathrm{~Hz}$
3 $458.3 \mathrm{~Hz}$
4 $550 \mathrm{~Hz}$
WAVES

173022 A police car horn emits a sound at a frequency $240 \mathrm{~Hz}$ when the car is at rest. If the speed of sound is $330 \mathrm{~m} / \mathrm{s}$, the frequency heard by an observer who is approaching the car at a speed of $11 \mathrm{~m} / \mathrm{s}$, is :

1 $248 \mathrm{~Hz}$
2 $244 \mathrm{~Hz}$
3 $240 \mathrm{~Hz}$
4 $230 \mathrm{~Hz}$
WAVES

173030 A star is moving towards the earth with a speed of $4.5 \times 10^{6} \mathrm{~m} / \mathrm{s}$. If the true wavelength of a certain line in the spectrum received from the star is $5890 \AA$, its apparent wavelength will be about $\left[\mathrm{c}=\mathbf{3} \times 10^{8} \mathrm{~m} / \mathrm{s}\right]$

1 $5890 \AA$
2 $5978 \AA$
3 $5802 \AA$
4 $5896 \AA$
WAVES

173020 A man is standing on the platform and one train is approaching and another train is going away with speed of $4 \mathrm{~m} / \mathrm{s}$, frequency of sound produced by train is $240 \mathrm{~Hz}$. What will be the no. of beats heard by him per second?

1 12
2 Zero
3 6
4 3
WAVES

173021 A source of sound of frequency $500 \mathrm{~Hz}$ is moving towards a stationary observer with velocity $30 \mathrm{~m} / \mathrm{s}$. The speed of sound is $330 \mathrm{~m} / \mathrm{s}$. The frequency heard by the observer will be :

1 $545 \mathrm{~Hz}$
2 $580 \mathrm{~Hz}$
3 $458.3 \mathrm{~Hz}$
4 $550 \mathrm{~Hz}$
WAVES

173022 A police car horn emits a sound at a frequency $240 \mathrm{~Hz}$ when the car is at rest. If the speed of sound is $330 \mathrm{~m} / \mathrm{s}$, the frequency heard by an observer who is approaching the car at a speed of $11 \mathrm{~m} / \mathrm{s}$, is :

1 $248 \mathrm{~Hz}$
2 $244 \mathrm{~Hz}$
3 $240 \mathrm{~Hz}$
4 $230 \mathrm{~Hz}$
WAVES

173030 A star is moving towards the earth with a speed of $4.5 \times 10^{6} \mathrm{~m} / \mathrm{s}$. If the true wavelength of a certain line in the spectrum received from the star is $5890 \AA$, its apparent wavelength will be about $\left[\mathrm{c}=\mathbf{3} \times 10^{8} \mathrm{~m} / \mathrm{s}\right]$

1 $5890 \AA$
2 $5978 \AA$
3 $5802 \AA$
4 $5896 \AA$
WAVES

173020 A man is standing on the platform and one train is approaching and another train is going away with speed of $4 \mathrm{~m} / \mathrm{s}$, frequency of sound produced by train is $240 \mathrm{~Hz}$. What will be the no. of beats heard by him per second?

1 12
2 Zero
3 6
4 3
WAVES

173021 A source of sound of frequency $500 \mathrm{~Hz}$ is moving towards a stationary observer with velocity $30 \mathrm{~m} / \mathrm{s}$. The speed of sound is $330 \mathrm{~m} / \mathrm{s}$. The frequency heard by the observer will be :

1 $545 \mathrm{~Hz}$
2 $580 \mathrm{~Hz}$
3 $458.3 \mathrm{~Hz}$
4 $550 \mathrm{~Hz}$
WAVES

173022 A police car horn emits a sound at a frequency $240 \mathrm{~Hz}$ when the car is at rest. If the speed of sound is $330 \mathrm{~m} / \mathrm{s}$, the frequency heard by an observer who is approaching the car at a speed of $11 \mathrm{~m} / \mathrm{s}$, is :

1 $248 \mathrm{~Hz}$
2 $244 \mathrm{~Hz}$
3 $240 \mathrm{~Hz}$
4 $230 \mathrm{~Hz}$
WAVES

173030 A star is moving towards the earth with a speed of $4.5 \times 10^{6} \mathrm{~m} / \mathrm{s}$. If the true wavelength of a certain line in the spectrum received from the star is $5890 \AA$, its apparent wavelength will be about $\left[\mathrm{c}=\mathbf{3} \times 10^{8} \mathrm{~m} / \mathrm{s}\right]$

1 $5890 \AA$
2 $5978 \AA$
3 $5802 \AA$
4 $5896 \AA$