Two stars P and Q have slightly different surface temperatures TP and TQrespectively, with TP > TQ. Both stars are receding from the earth with speeds vP and vQ relative to the earth. The wavelength of light at which they radiate the maximum energy is found to be same for both:
Let and be the actual wavelength at which P and Q radiate maximum energy. By Wien’s law,
As these wavelengths appear equal on reaching the earth, has increased more than Hence
A bob of mass m is oscillating as a simple pendulum with maximum amplitude θm. What is the maximum tension in the string?
A certain amount of acoustic energy is emitted in a uniform hemispherical pattern from a point source. At a distance of 5 m form the source the intensity is 5 W/m2. At a distance of 15 m the intensity will be:
A 10 W source of sound of frequency 1000 Hz sends out waves in air. The displacement amplitude at a distance of 10 m from source will be: (Given velocity of sound = 350 m/s and density of air = 1.29 kg/m3)
The air in a closed tube 34 cm long is vibrating with 2 nodes and 2 antinodes and the temperature is 51oC. What is the wavelength of waves produced in air outside the tube when the temperature of air is 16oC?
The fundamental frequency of a longitudinal vibrating of a rod clamped at its centre is 1500 Hz. If the mass of the rod is 96 g the increase in its total length produced by a stretching force of 10 kg weight will be:
If there are three sources of sound of equal intensity with frequencies 300, 301 and 302, the number of beats heard per second will be:
The speed of sound waves in dry air at NTP is 332 m/sec. Assuming air to be composed of oxygen and nitrogen in the ratio 1:4 and the densities of oxygen and nitrogen at NTP to be in the ratio 8:7, the velocity of sound in oxygen will be equal to:
The speed of sound waves in a mixture of helium and neon at 300 K and at a pressure of 76 cm of Hg was found to be 758 m/sec. The densities of helium and neon are respectively 0.1785 and 0.8999 g/litre and γ of mixture is 1.667. What is the ratio of He and Ne in the mixture?
The number of possible overtones of air column in a closed pipe of length 83.2 cm and of diameter 6 cm whose frequencies lie below 1000 Hz will be [velocity of sound = 340 m/s]:
In a resonance column experiment, a long tube, open at the top, is calmed vertically. By a separate device, water level inside the tube can be moved up or down. The section of the tube from the open end to the water level acts as a closed organ pipe. A vibrating tuning fork is held above the open end, and the water level is gradually pushed down. The first and the second resonances occur when the water level is 24.1 cm and 74.1 cm respectively below the open end. The diameter of the tube is: