21.

A particle is executing a simple harmonic motion. Its maximum acceleration is α and maximum velocity is β. Then, its time period of vibration will be 

• β²/α²

• α/β

• β²/α

• β²/α

Two vessels separately contain two ideal gases A and B the same temperature, the pressure of A being twice that of B. Under such conditions, the density of A is found to be 1.5 times the density of B. The ratio of molecular weight of A and B is

• 2/3

• 3/4

• 2

• 2

An ideal gas is compressed to half its initial volume by means of several process. Which of the process results in the maximum work done on the gas?

• Adiabatic

• Isobaric

• Isochoric 

• Isochoric 

A source of sound S emitting waves of frequency 100 Hz and an observer O are located at some distance from each other. The source is moving with a speed of 19.4 ms^-1 at an angle of 60^o with the source observer is at rest. the apparent frequency observed by the observer (velocity of sound in air 330 ms^-1) is 

• 100 Hz

• 103 Hz

• 106 Hz

• 106 Hz

A proton and an alpha particle both enter a region of uniform magnetic field B, moving at angles to the field B. If the radius of circular orbits for both the particles is equal and the kinetic energy acquired by proton is 1 MeV, the energy acquired by the alpha particle will be

• 4 MeV

• 0.5 Mev

• 1.5 MeV

• 1.5 MeV

If potential (in volts) in a region is expressed as V (x, y, z) = 6 xy-y +2 yz, the electric field (in N/C) at point (1,1,0) is 

A parallel-plate air capacitor has capacity C, a distance of separation between plates is d a potential difference V is applied between the plates. Force of attraction between the plates of the parallel plate air capacitor is 

The energy of the EM waves is of the order of 15 keV. To which part of the spectrum does it belong?

• X - rays

• infrared rays

• Ultraviolet rays

• Ultraviolet rays

In the given figure, a diode D is connected to an external resistance R = 100 Ω and an e. m. f of 3.5 V. If the barrier potential developed across the diode is 0.5 V, the current in the circuit will be 

• 30 mA

• 40 mA

• 20 mA

• 20 mA