Physics Past Questions and Answers

Birds can perch safely on overhead electric power cables without being electrocuted because

A Birds can withstand high p.d. of the electric power cables
B Any accumulated charge on the birds is quickly dissipated
C The feet of the birds are well insulated
D The current is a.c. and has particular direction
E There is no p.d between the birds and the cables

Question 157:

A cell of e.m.f. 1.5 V and internal resistance of 2.59 is connected in series with an ammeter of resistance 0.59 and a resistor of resistance 7.09. Calculate the current in the circuit.

A 0.15 A
B 0.20 A
C 0.60A
D 3.00A
E 6.67 A.

Question 158:

A rectangular coil of wire can rotate in a magnetic field. The ends of the coil are soldered to the two halves of a split ring. Two carbon brushes are made to press lightly against the split ring and when these are connected in circuit with a battery and rheostat, the coil rotates. This is a description of

A A suspended- coil vanometer
B A moving-cell ammeter
C A d.c generator
D An electric motor
E An induction coil,

Question 159:

How long will it take to heat 3 kg of water from 28^oC to 88^oC in an electric taking a current of 6 A from an e.m.f. source of 220V?

A 96s
B 1.20s
C 570s
D 600s
E 1200s

Question 160:

Which of the following reduce(s) the effect of the back e.m.f. generated in the primary coil of an induction coil? The capacitor in the circuit II. The make and break contact in the circuit III. The ratio of turns in the secondary to that in the primary

A L only
B II only
C I and II only
D II and III only
E I, II and III.