Physics Past Questions and Answers

A lamp rated 100W, 240V is lit for 5hours. Calculate the cost of lighting the lamp if 1kWh of electrical energy cost N5.

A N2.50
B N3.20
C N6.50
D N9.60

Question 1807:

A battery of e.m.f 3.0V is connected across a potentiometer wire AB of length 10\(\Omega m^{-1}\) as illustrated in the diagram above. If the jockey J makes contact at the 30cm mark, determine the resistance of length AJ and voltage across AJ.

A 3.0\(\Omega\); 0.9V
B 3.0\(\Omega\); 3.0V
C 3.3\(\Omega\); 0.3V
D 3.3\(\Omega\); 9.0V

Question 1808:

The main reason why a.c. is transmitted at very high voltage and low current is that

A Flows faster through the conductor
B Can be stepped down
C Is cheaper to generate
D Reduces heat loss

Question 1809:

The diagram above illustrates two charged bodies, X and Y seperated by a distance r. Each body has charge q and mass m. Which of the following statements about the electrostatic force \(F_{e}\) and fravitational force \(F_{g}\) acting between the bodies is correct?

A \(F_{e}\) is attraction while \(F_{g}\) is repulsion
B Both \(F_{e}\) and \(F_{g}\) are that of repulsion
C Both \(F_{e}\) and \(F_{g}\) is that of attraction
D \(F_{e}\) is repulsion while \(F_{g}\) is attraction

Question 1810:

The opposition offered to an alternating current in a C-R series circuit is known as

A Impedance
B Resistance
C Reactance
D Friction