Waves Test - 96...

Intensity level 200 cm from a source of sound is 80 dB. If there is no loss of acoustic power in air and intensity of threshold hearing is 10^–2 Wm^–2 then, what is the intensity level at a distance of 4000 cm from source?

In the musical octave `Sa\', \'Re\', \'Ga\'

A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at distances of 2m and 3m respectively from the source. The ratio of the intensities of the waves at P and Q is

Learned Indian classical vocalists do not like the accompaniment of a harmonium because

Each of the properties of sound listed in column A primarily depends on one of the quantities in column B. Choose the matching pairs from two columns

In a large room, a person receives direct sound waves from a source 120 metres away from him. He also receives waves from the same source which reach him, being reflected from the 25 metre high ceiling at a point halfway between them. The two waves interfere constructively for wavelength of

A train has just completed a U-curve in a track which is a semicircle. The engine is at the forward end of the semicircular part of the track while the last carriage is at the rear end of the semicircular track. The driver blows a whistle of frequency 200 Hz. Velocity of sound is 340 m/sec. Then the apparent frequency as observed by a passenger in the middle of a train when the speed of the train is 30 m/sec is

Two identical flutes produce fundamental notes of frequency 300 Hz at 27°C. If the temperature of air in one flute is increased to 31°C, the number of the beats heard per second will be

A string of length 0.4 m and mass 10^–2 kg is tightly clamped at its ends. The tension in the string is 1.6 N. Identical wave pulses are produced at one end at equal intervals of time ∆t. The minimum value of ∆t which allows constructive interference between successive pulses is

Two identical stringed instruments have frequency 100 Hz. If tension in one of them is increased by 4% and they are sounded together then the number of beats in one second is