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Why is the ceiling and wall behind the stage of good conference halls or concert halls made curved?

Answer: Ceiling and wall behind the stage of good conference halls or concert halls made curved to ensure the reflected sound equally to all the... View Article

For hearing the loudest ticking sound heard by the ear, find the angle x in the Fig.

Answer: The angle of incidence is always equal to the Angle of reflection The angle of Incidence = 900-500= 400 The angle of incidence is equal... View Article

The sound produced by a thunderstorm is heard 10 s after the lightning is seen. Calculate the approximate distance of the thunder cloud. (Given the speed of sound = 340 m s–1.)

Answer: Lightning travels at the speed of light and reaches the viewer very quickly. As a result, the sound takes the entire ten seconds between... View Article

If any explosion takes place at the bottom of a lake, what type of shock waves in water will take place?

Answer: Longitudinal waves An explosion in a lake produces shock waves, which result in a massive increase in water pressure. As a result, a... View Article

Why do we hear the sound produced by the humming bees while the sound of vibrations of a pendulum is not heard?

Answer: The human ear can detect sounds in the range of 20Hz-20KHz. These are called Audible Sounds. Frequencies below 20Hz and greater than... View Article

A girl is sitting in the middle of a park of dimension 12 m × 12 m. On the left side of it there is a building adjoining the park and on right side of the park, there is a road adjoining the park. A sound is produced on the road by a cracker. Is it possible for the girl to hear the echo of this sound? Explain your answer.

Answer: Echo can be heard if the gap between the original sound and reflected sound received by the listener is around 0.1 sec. Speed of sound in... View Article

Which of the above two graphs (a) and (b) (Fig.) representing the human voice is likely to be the male voice? Give the reason for your answer.

Answer: The pitch of a male voice is lighter than the pitch of a female hence the graph a represent male voice. The male voice is represented... View Article

The given graph shows the displacement versus time relation for a disturbance travelling with a velocity of 1500 m s^-1. Calculate the wavelength of the disturbance.

Answer: The particle of the medium oscillates during sound propagation. We can observe from the graph that one complete oscillation takes 2... View Article

Before playing the orchestra in a musical concert, a sitarist tries to adjust the tension and pluck the string suitably. By doing so, he is adjusting (a) intensity of sound only (b) amplitude of sound only (c) frequency of the sitar string with the frequency of other musical instruments (d) loudness of sound

Answer: (c) frequency of the sitar string with the frequency of other musical instruments Artists adjust the frequencies before beginning to play... View Article

Infrasound can be heard by (a) dog (b) bat (c) rhinoceros (d) human beings

Answer: (c) rhinoceros An earthquake is the shaking of the surface of Earth due to the sudden release of energy in the Earth’s crust, as a... View Article

Earthquake produces which kind of sound before the main shock wave begins (a) ultrasound (b) infrasound (c) audible sound (d) none of the above

Answer: One of the prominent examples of infrasound waves is earthquake waves. Earthquake waves can be classified into three categories: The... View Article

In the curve half the wavelength is (a) A B (b) B D (c) D E (d) A E

Answer: (b) B D Wavelength is the distance between two consecutive troughs. In the graph half, the wavelength will BD. The wavelength of... View Article

When we change feeble sound to loud sound we increase its (a) frequency (b) amplitude (c) velocity (d) wavelength

Answer: (b) amplitude Loudness of sound is proportional to amplitude. When amplitude increases feeble sound change to loud sound. Distance... View Article

Sound travels in air if (a) particles of medium travel from one place to another (b) there is no moisture in the atmosphere (c) disturbance moves (d) both particles as well as disturbance travel from one place to another.

Answer: (c) disturbance moves Sound waves propagate by vibrating in its own position. Whereas disturbance created by vibration of particles moves... View Article

A key of a mechanical piano struck gently and then struck again but much harder this time. In the second case (a) sound will be louder but pitch will not be different (b) sound will be louder and pitch will also be higher (c) sound will be louder but pitch will be lower (d) both loudness and pitch will remain unaffected

Answer: (a) sound will be louder but pitch will not be different Pitch is a perceptual property of sounds that allows their ordering on a... View Article

Note is a sound (a) of mixture of several frequencies (b) of mixture of two frequencies only (c) of a single frequency (d) always unpleasant to listen

Answer: (a) of mixture of several frequencies A sound of a single frequency is called a tone. A sound produced with a mixture of several... View Article

Two stones are thrown vertically upwards simultaneously with their initial velocities u1 and u2 respectively. Prove that the heights reached by them would be in the ratio of u1² :u2² ( Assume upward acceleration is –g and downward acceleration to be +g ).

Answer: We know for upward motion v2 = u2 - 2gh h = (u2 - v2)/2g At highest point v = 0 Therefore h = u2/2g For the first ball h1 = u21/2g For... View Article

Obtain a relation for the distance travelled by an object moving with a uniform acceleration in the interval between 4^th and 5^th seconds.

Answer: From second equation of motion, s = ut + 1/2at2 The displacement after t = 5 seconds will be s5= 5u + 1/2a52 The displacement after t = 4... View Article

An electron moving with a velocity of 5 × 10⁴ m/s enters into a uniform electric field and acquires a uniform acceleration of 104 ms^-2 in the direction of its initial motion. (i) Calculate the time in which the electron would acquire a velocity double of its initial velocity. (ii) How much distance the electron would cover in this time?

Answer: Given Initial velocity (u) = 5 × 104 m/s Acceleration (a) = 104 ms-2 (i) Calculate the time in which the electron would acquire a... View Article

Using following data, draw time – displacement graph for a moving object: Use this graph to find average velocity for first 4 s, for next 4 s and for last 6 s.

Answer: Average velocity for the first 4s = = (4 - 0)/(4 - 0) = 4/4 = 1 ms-1 Average velocity of next 4 s = v = = 0 Average velocity for... View Article

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