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\(kg^{-1}K{-1}\)

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 \(5.9\times10^{-7}\)m, calculate its wavelength in the medium

A. \(2.5\times10^{-7}\)m
B. \(3.8\times10^{-7}\)m
C. \(4.6\times10^{-7}\)m
D. \(5.2\times10^{-7}\)m
E. \(6.1\times10^{-7}\)m

Question 43:

• WAEC 1994

The density of a body is \(5\times10^3kgm{^-3}\) 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\(cm^3\) while that of ice is 0.9\(cm^3\), calculate the volume change when 90g of ice is completely melted

A. 0\(cm^3\)
B. 9\(cm^3\)
C. 10\(cm^3\)
D. 90\(cm^3\)
E. 100\(cm^3\)

Question 45:

• WAEC 1994

(a) What is meant by the statement: The specific heat capacity of copper is \(400 J kg^{-1}K^{-1}\)?
(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 = \(4.2 J g^{-1}K^{-1}\)) (Specific heat capacity of copper = \(0.4 Jg^{-1}K^{-1}\)).