Physics 1992 Waec Past Questions and Answers

Question 41 :

• WAEC 1992

A negatively charged rod is brought near the cap of a gold-leaf electroscope. The cap is earthed momentarily while the rod is near to it. The rod is then removed. Which of the following is correct?

A. The cap will be positively charged and the negatively charged leaves will diverge
B. The cap will be negatively charged and the positively charged leaves will diverge
C. The cap and the leaves will be positively charged
D. The cap and the leaves will be negatively charged.
E. The leaves will not diverge because the cap has been earthed.

Question 42 :

• WAEC 1992

Calculate the rate at which energy is used up in the circuit illustrated by the diagram

A. 0 W
B. 2 W
C. 4 W
D. 8 W
E. 16 W

Question 43 :

• WAEC 1992

Which of the following is not a consequence of hydrogen bubbles covering the copper plate of a primary cell?

A. Polarization
B. Local action
C. Formation of hydrogen electrode
D. Increase in the resistance of the cell
E. Generation of less current by the cell

Question 44 :

• WAEC 1992

Calculate the length of a constantan wire of cross- sectional area 4 π x 10^-8m² and resistivity 1.1 x 10^-6 Ω m required to construct a standard resistor of resistance 21 Ω. [Take π = 22/7]

A. 0.42m
B. 2.40 m
C. 6.25 m
D. 183.75 m
E. 590.00 m

Question 45 :

• WAEC 1992

In a domestic circuit, electrical appliances and lamps are arranged in parallel across the mains so as to enable the

A. Same current to flow through the electrical appliances and the lamps
B. Maximum energy to be consumed at least cost
C. Same fuse to be used for the electrical appliances and the lamps
D. Voltage across the appliances not to be affected when the lamps are switched on and off
E. Heat losses to be minimized