Physics Past Questions and Answers

The combination of sound waves with different frequencies is known as

A Interference
B Diffraction
C Superposition
D Forced vibration
E Resonance

Question 17:

Why does a piece of cork float on water?

A There is no upthrust on it when completely immersed in water
B The upthrust on it when completely immersed in water is greater than its weight in air
C The upthrust on it when completely immersed in water is less than its weight in air
D Its specific gravity is greater than that of water
E Its specific gravity is the same as that of water

Question 18:

A rod of length 10cm is heated through 100^oC and its final length is 10.26cm. What is the co-efficient of linear expansion of the rod?

A 0.026 per degree centigrade
B 0.00026 per degree centigrade
C 0.26 per degree centigrade
D 1.0026 per degree centigrade
E 0.0026 per degree centigrade

Question 19:

If the refractive index of a medium is V2, what is the critical angle?

A 45^o
B 50^o12'
C 56^o25'
D 75^o
E 90^o

Question 20:

In copper plating, a current of 0.5A is allowed for cathode area of 100cm². If this current is maintained constant for 100 minutes, the thickness of the copper deposited will be approximately (the electrochemical equivalent of copper = 0.0003g/^oC, density of copper = 10^-4g/cm³ )

A 10^-2mm
B 10^-3mm
C 10^-4mm
D 10^-5mm
E 10^-6mm