PUC Science कक्षा ११ - Karnataka Board PUC Question Bank Solutions for Physics

A heavy string is tied at one end to a movable support and to a light thread at the other end as shown in following figure. The thread goes over a fixed pulley and supports a weight to produce a tension. The lowest frequency with which the heavy string resonates is 120 Hz. If the movable support is pushed to the right by 10 cm so that the joint is placed on the pulley, what will be the minimum frequency at which the heavy string can resonate?

Two sources of sound S₁ and S₂ vibrate at same frequency and are in phase. The intensity of sound detected at a point P as shown in the figure is I₀. (a) If θ equals 45°, what will be the intensity of sound detected at this point if one of the sources is switched off? (b) What will be the answer of the previous part if θ = 60°?

In a standing wave pattern in a vibrating air column, nodes are formed at a distance of 4.0 cm. If the speed of sound in air is 328 m s⁻¹, what is the frequency of the source?

The separation between a node and the next antinode in a vibrating air column is 25 cm. If the speed of sound in air is 340 m s⁻¹, find the frequency of vibration of the air column.

The first overtone frequency of a closed organ pipe P₁ is equal to the fundamental frequency of a open organ pipe P₂. If the length of the pipe P₁ is 30 cm, what will be the length of P₂?

Consider the situation shown in the figure.The wire which has a mass of 4.00 g oscillates in its second harmonic and sets the air column in the tube into vibrations in its fundamental mode. Assuming that the speed of sound in air is 340 m s⁻¹, find the tension in the wire.

The fundamental frequency of a closed pipe is 293 Hz when the air in it is a temperature of 20°C. What will be its fundamental frequency when the temperature changes to 22°C?

A source of sound with adjustable frequency produces 2 beats per second with a tuning fork when its frequency is either 476 Hz of 480 Hz. What is the frequency of the tuning fork?

A tuning fork produces 4 beats per second with another tuning fork of frequency 256 Hz. The first one is now loaded with a little wax and the beat frequency is found to increase to 6 per second. What was the original frequency of the tuning fork?

Show that if the room temperature changes by a small amount from T to T + ∆T, the fundamental frequency of an organ pipe changes from v to v + ∆v, where \[\frac{∆ v}{v} = \frac{1}{2}\frac{∆ T}{T} .\]

A cylindrical tube, open at both ends, has a fundamental frequency v. The tube is dipped vertically in water so that half of its length is inside the water. The new fundamental frequency is

A piano wire A vibrates at a fundamental frequency of 600 Hz. A second identical wire Bproduces 6 beats per second with it when the tension in A is slightly increased. Find the the ratio of the tension in A to the tension in B.

A tuning fork of frequency 256 Hz produces 4 beats per second with a wire of length 25 cm vibrating in its fundamental mode. The beat frequency decreases when the length is slightly shortened. What could be the minimum length by which the wire we shortened so that it produces no beats with the tuning fork?

Two electric trains run at the same speed of 72 km h⁻¹ along the same track and in the same direction with separation of 2.4 km between them. The two trains simultaneously sound brief whistles. A person is situated at a perpendicular distance of 500 m from the track and is equidistant from the two trains at the instant of the whistling. If both the whistles were at 500 Hz and the speed of sound in air is 340 m s⁻¹, find the frequencies heard by the person.

A small source of sound oscillates in simple harmonic motion with an amplitude of 17 cm. A detector is placed along the line of motion of the source. The source emits a sound of frequency 800 Hz which travels at a speed of 340 m s⁻¹. If the width of the frequency band detected by the detector is 8 Hz, find the time period of the source.

A boy riding on his bike is going towards east at a speed of 4√2 m s⁻¹. At a certain point he produces a sound pulse of frequency 1650 Hz that travels in air at a speed  of 334 m s⁻¹. A second boy stands on the ground 45° south of east from his. Find the frequency of the pulse as received by the second boy.

A sound source, fixed at the origin, is continuously emitting sound at a frequency of 660 Hz. The sound travels in air at a speed of 330 m s⁻¹. A listener is moving along the lien x= 336 m at a constant speed of 26 m s⁻¹. Find the frequency of the sound as observed by the listener when he is (a) at y = − 140 m, (b) at y = 0 and (c) at y = 140 m.

A train running at 108 km h⁻¹ towards east whistles at a dominant frequency of 500 Hz. Speed of sound in air is 340 m/s. What frequency will a passenger sitting near the open window hear? (b) What frequency will a person standing near the track hear whom the train has just passed? (c) A wind starts blowing towards east at a speed of 36 km h⁻¹. Calculate the frequencies heard by the passenger in the train and by the person standing near the track.

A boy riding on a bicycle going at 12 km h⁻¹ towards a vertical wall whistles at his dog on the ground. If the frequency of the whistle is 1600 Hz and the speed of sound in air is 330 m s⁻¹, find (a) the frequency of the whistle as received by the wall (b) the frequency of the reflected whistle as received by the boy.