Physics Past Questions and Answers

An immersion heater rated 2.0A, 240V is used to boil water from temperature 52°c to 100°c. If the mass of the water is 2.5kg. determine the time taken to boil the water.
[specific heat capacity of water = 4.2 x 10³ jkg^-1 k^-1]

A 1.05 x 10³s
B 1.05 x 10⁵s
C 1.05 x 10²s
D 1.05 x 10⁴s

Question 7:

The thermos flask is designed to?

A Prevent heat loss or gain by conduction, convection amd radiation
B Store hot tea or water
C Prevent heat gain by conduction, convection and radiation
D Prevent head lost conduction, convention and radiation

Question 8:

what is likely to happen if the glass of a thermometer expands more upon heating than the liquid inside?

A The glass will break
B The glass will shrink
C The liquid will rise up in the stem
D The liquid will go down in the stem

Question 9:

A drop of petrol makes a finger colder than a drop of water would because?

A Petrol takes its latent heat of veporization from the finger
B Petrol takes its latent heat of fusion from the finger
C Water is more viscious than petrol
D Water has higher surface tension dan petrol

Question 10:

A cell of internal resistance r is connected to an external resistor R. The conductor for maximum power transfer is?

A R < r
B R = r
C R = 2r
D R > r