A simple pendulum has a metal bob which is negatively charged.If it is allowed to oscillate above a positively charged metallic plate then its time period will :
increase
decrease
remain the same
become zero
When a body executes vibrations under the action of an external periodic force, then the vibrations of the body are called
Forced vibrations
Damped vibrations
Free vibrations
Natural oscillations
When an external periodic force is applied, a body does not vibrate with its
Artificial vibrations
The speed of the bob of an oscillating pendulum is zero :
at the mean position
at an extreme position
between the mean position and the left extreme
between the mean position and the right extreme
Delhi Radio Station transmits musical programmes at 219 m wavelength and 1300 Hz frequency.Calculate the velocity of radio waves.
2.847 x 10-5 m/s
3.148 x 105 m/s
2.847 x 105 m/s
3.84 x 10-5 m/s
When the sound of certain frequency, travels through air with a velocity, the value of v is
v = c/λ
v = λ/c
v = cλ
λc
A longitudinal wave travels from east to west in air.In which direction do the particles of air move?
East to west
West to east
North to south
South to north
S.I unit of wave length (λ) is
centimetre
millimetre
kilometre
metre
A pendulum vibrates with a time period of 1 second.The sound produced by it is
supersonic
audible
infrasonic
ultrasonic
An object moving at a speed greater than that of sound is said to be moving at :
ultrasonic speed
sonic speed
infrasonic speed
supersonic speed
