Physics 2020 Waec Past Questions and Answers

Question 11 :

• WAEC 2020

Which of the following statements explain why hot soapy water is more effective in cleaning oil-stained dishes?

A. The oil on the dishes repels the soap
B. Soap and heat decrease the surface tension of oil
C. Soap increases the surface tension of oil and water
D. Hot water increases the surface tension of oil

Question 12 :

• WAEC 2020

An electrical device has 50 turns in its primary coil and 20 turns in the secondary coil. The device can be a\an?

A. Step-up transformer
B. Step-down transformer
C. D.c generator
D. A.c generator

Question 13 :

• WAEC 2020

The earpiece of a telephone handset converts energy from

A. Electrical to sound
B. Sound to electrical
C. Sound to electrical
D. Sound to radio wave

Question 14 :

• WAEC 2020

Two identical cups containing the same volume of water at 45°C and 5°C, are left in a room at 25°C. Which of the following graphs correctly illustrates the variation of temperature with time?

A. A
B. B
C. C
D. D

Question 15 :

• WAEC 2020

A ray of light travelling from glass into ethyl alcohol is incident at the boundary at an angle of incidence 3\(^o\). Calculate the angle of refraction. [Refractive index of glass =1.5; refractive index of ethyl alcohol = 1.36]

A. 27\(^o\)
B. 33.5\(^o\)
C. 51.7\(^o\)
D. 72.8\(^o\)