Two wires, \(A\) and \(B,\) of a musical instrument 'Sitar' produce \(3\) beats per second. If the tension of \(B\) is raised, the number of beats becomes \(1\) beat per second. If the frequency of \(A\) is \(450~\text{Hz}\), then the original frequency of \(B\) will be:
1. \(447~\text{Hz}\)
2. \(453~\text{Hz}\)
3. \(449~\text{Hz}\)
4. \(451~\text{Hz}\)
A train moves towards a stationary observer at 50 m/s. The train sounds a whistle and its frequency is registered by the observer as . If the train's speed is increased by 25 m/s, the frequency registered is . If the speed of sound is 300 m/s, then : is:
1. 3:5
2. 5:7
3. 7:9
4. 9:10
1. | \(l\) | 2. | \(2l\) |
3. | \(3l\) | 4. | \(4l\) |
1. | Wavelength of the component waves is \(10~\text{cm}.\) |
2. | The separation between a node and the nearest antinode is \(2.5~\text{cm}.\) |
3. | Frequency of the component wave is \(0.25~\text{Hz}\). |
4. | All of these |
1. | \(6\) | 2. | \(5\) |
3. | \(4\) | 4. | \(3\) |
1. | \(1:1\) | 2. | \(5:2\) |
3. | \(3:2\) | 4. | \(4:5\) |
A car with a siren is moving towards a hill at a speed of 108 km/h. A person is standing at the foot of the hill. The frequency observed by a person is: (frequency of siren is 600 Hz, velocity of sound is 330 m/s)
1. 720 Hz
2. 660 Hz
3. 600 Hz
4. 630 Hz