Waec Physics 2006 Past Questions and Answers

Question 21:

• WAEC 2006

The sagging of overhead electrical cables is the consequence of

A. Linear expansivity
B. Superficial expansivity
C. Cubic expansivity
D. Conductivity

Question 22:

• WAEC 2006

The silvered surface in a vacuum flask reduces heat loos due to

A. Conduction
B. Convection
C. Radiation
D. Evaporation

Question 23:

• WAEC 2006

How long will it take to heat 3kg of water from 28^oC to 88^oC in an electric kettle taking 6a from a 220V supply? [specific heat capacity of water = 4180 J kg^-1K^-1]

A. 120s
B. 570s
C. 600s
D. 836s

Question 24:

• WAEC 2006

The amount of energy required to change a kilogram of ice in water without a change in temperature is

A. Heat capacity of ice
B. Specific heat capacity
C. Specific latent heat of vaporisation of ice
D. Specific latent heat of fusion of ice

Question 25:

• WAEC 2006

A quantity of steam at 100^oC condenses to water at the same temperature by releasing 6.9 x 10⁴J of energy. Calculate the mass of the condensed steam. [specific latent heat of vaporization of eater = 2.3 x 10⁶ J kg^-1]

A. 3.0 x 10^-1 kg
B. 3.0 x 10^-2 kg
C. 3.0 x 10^-3 kg
D. 3.0 x 10^-4 kg