Waec Physics 1994 Past Questions and Answers

Question 41:

• WAEC 1994

Calculate the time taken to heat 2kg of water from 50°C to 100°C in an electric kettle taking 5A, from a 210V supply. (Specific heat capacity of water = 4200$k{g}^{-1}K-1$

A. 2.5 minutes
B. 5.7 minutes
C. 6.7 minutes
D. 7.5 minutes
E. 9.5 minutes

Question 42:

• WAEC 1994

A light wave travels from air into a medium of refractive index 1.54. If the wavelength of the light in air is $5.9\times {10}^{-7}$m, calculate its wavelength in the medium

A. $2.5\times {10}^{-7}$m
B. $3.8\times {10}^{-7}$m
C. $4.6\times {10}^{-7}$m
D. $5.2\times {10}^{-7}$m
E. $6.1\times {10}^{-7}$m

Question 43:

• WAEC 1994

The density of a body is $5\times {10}^{3}kgm{}^{-}3$ and it weighs 1N in air. Calculate the apparent weight of the body when totally immersed in water. (Density of water =\(10^3kgm{-3}, g= 10ms^{-2}

A. 0.02N
B. 0.08N
C. 0.20N
D. 0.80N
E. 1N

Question 44:

• WAEC 1994

The density of water is 1g$c{m}^3$ while that of ice is 0.9$c{m}^3$, calculate the volume change when 90g of ice is completely melted

A. 0$c{m}^3$
B. 9$c{m}^3$
C. 10$c{m}^3$
D. 90$c{m}^3$
E. 100$c{m}^3$

Question 45:

• WAEC 1994

(a) What is meant by the statement: The specific heat capacity of copper is $400Jk{g}^{-1}{K}^{-1}$?
(b)(i) Describe an experiment to determine the specific heat capacity of copper using a copper ball.
(ii) State two precautions necessary to obtain accurate results
(iii) A piece of copper ball of mass 20 g at 200°C is placed in a copper calorimeter of mass 60 g containing 50 g of water at 30°C, ignoring heat losses, calculate the final steady temperature of the mixture (Specific heat capacity of water = $4.2J{g}^{-1}{K}^{-1}$) (Specific heat capacity of copper = $0.4J{g}^{-1}{K}^{-1}$).