Physics Past Questions and Answers

The wavelength of a stationary wave is 24.0cm. What is the distance between a node and the next antinodes?

A 6.0cm
B 12.0cm
C 18.0cm
D 24.0cm
E 48.0cm

Question 72:

How much heat is required to convert 5.0g of ice at 0 ° C to water at the boiling point? (Specific latent heat of ice = 336Jg^-1 specific heat capacity of water = 4.2Jg^-1K^-1)

A 420 J
B 1680 J
C 1701 J
D 2100 J
E 3780 J

Question 73:

What gives rise to the line spectra observed in atoms?

A Change of an electron from a higher to a lower energy level in the atom
B Disturbed protons in the nucleus
C Excitation of an electron in the atom
D Kinetic energy of a moving atom
E Potential energy of an electron inside an atom

Question 74:

A lead-acid accumulator is used in preference to a dry battery in a car because ____________

A A dry battery cannot supply the necessary high voltage
B A dry battery would not operate on a cold frosty morning
C The accumulator can give a bigger current and can be recharged
D The accumulator can supply a.c
E The chemicals used in a dry battery constitute a fire hazard.

Question 75:

A metal has a work function of 3.0 eV. What is the threshold frequency of the metal when electrons are just liberated from the metal.(1 eV = 1.6 × 10-19J; h = 6.6 × 10-34Js)

A 4.8 × 10^-19Hz
B 9.3 × 10^-7Hz
C 4.8 × 10¹⁴Hz
D 7.3 × 10¹⁴Hz
E 9.3 × 10¹⁴Hz