Physics Past Questions and Answers

A heating coil rated 1000 W is used to boil off completely 2 kg of boiling water. the time required to boil of the water is_______
[Special latent heat of Vaporization of water = 2.3 x 10⁶ Jkg^-1]

A 1.15 x 10⁴s
B 1.15 x 10³s
C 4.6 x 10⁴s
D 4.6 x 10³s

Question 17:

It is observed that water will wet a clean glass because the

A Cohesion of water to glass is stronger than the cohesion of water molecules
B Adhesion of water molecules is weaker than the cohesion of water to glass
C Cohesion of water to glass is weaker than the cohesion of water molecules
D Adhesion of water molecules is stronger than the cohesion of water molecules

Question 18:

A man standing 2 m from a charcoal fire is warmed mainly by

A Convection
B Radiation
C Refraction
D Conduction

Question 19:

Metal cables are used as telephone wires because

A They are cheap
B They are sourced locally
C The speed of sound in them is very low
D The speed of sound in them is very high

Question 20:

Musical instruments playing the same note can be distinguished from one another owing to the differences in their

A Quality
B Pitch
C Intensity
D Loudness