Physics Past Questions and Answers

A freshly demagnetized bar magnet is placed in the East-West direction to ensure that

A The molecular magnets remain randomly arranged.
B The molecular magnets are properly aligned
C It is affected by the earth's magnetic field
D The magnetic domains are within the earth's field

Question 1922:

Which of the following graphs of a charge Q against potential difference V across the capacitor is correct?

Question 1923:

A small amount of air is introduced into the vacuum above the mercury in a mercury barometer tube. The mercury level goes down because the air molecules

A Heat the mercury and make it expand
B Increase the pressure above the mercury.
C Cool the mercury and make it contract.
D Decrease the pressure above the mercury

Question 1924:

Calculate the quantity of heat needed to change the temperature of 60g of ice at 0 °C to 80 °C. [specific latent heat of fusion of ice= 3.36 x 10\(^5\) Jkg\(^{-1}\) specific heat capacity of water 4.2 x 10\(^3\) J kg\(^{-1}\) K\(^{-1}\)]

A 4.80 kJ
B 20.16 kJ
C 40.32 kJ
D 22.17 kJ

Question 1925:

The wire of a platinum resistance thermometer has d resistance of 3.5\(\Omega\) at 0 °C and 10.52\(\Omega\) at 100°C. Calculate the temperature of the wire when its resistance is 7.5\(\Omega\).

A 78 °C
B 25 \(^o\)C
C 30\(^o\)C
D 57 \(^o\)C