1991 - WAEC Physics Past Questions and Answers - page 5
41
Two objects of masses 80kg and 50kg are separated by a distance of 0.2m. If the gravitational constant is 6.6 x 10-11Nm kg, calculate the gravitational attraction between them.
A
4.9 x 10-9N
B
1.3 x 10-6N
C
6.6 x 10-8N
D
6.6 x 10-6N
42
Two capacitors C1 and C2 are connected as shown in the diagram. The capacitance C2 is twice C1 when the key is opened the energy stored up in C1 is W. If the key is later closed and the system is allowed to attain electrical equilibrium, the total energy stored in the system will be
A
\(\frac{1}{2}\)W
B
\(\frac{2}{3}\)W
C
W
D
2w
43
In which of the points labelled A, B, C, D and E on the conductor shown would electric charge tend to concentrate most?
A
A
B
B
C
C
D
D
44
Which of the following is stored by dry Leclanche cell?
A
chemical energy
B
nuclear energy
C
solar energy
D
heat energy
45
Using the data in the circuit illustrated above, calculate the value of R
A
0.02\(\Omega\)
B
0.05\(\Omega\)
C
5.00\(\Omega\)
D
20.00\(\Omega\)
46
A 90W immersion heater is used to supply energy for 5 minutes. The energy supplied is used to completely melt 160g of a solid at its melting point. Calculate the specific latent heat of the solid.
A
2.81jg-1
B
6.25Jg-1
C
8.89Jg-1
D
168.75Jg-1
47
In the circuit above R is a resistor whose resistance increases with increases with increase in temperature L1 and L2 are identical lamps. If the temperature of R increases
A
L1 becomes brighter and L2 becomes dimmer
B
L1 becomes brighter and L2 does not change
C
L2 becomes dimmer and L1 does not change
D
L1 becomes dimmer and L2 does not change
48
A house is supplied with a 240V a.c mains. To operate a door bell rated at 8v, a transformer is used if the number of turns in the primary coil of the transformer is 900. calculate the number of turns in the secondary coil of the transformer
A
30
B
240
C
248
D
450
49
The diagram above shows a current carrying wire between the poles of a magnet. In which direction would the wire tend to move?
A
into the paper
B
out of the paper
C
towargs the north pole of the magnet
D
towards the south pole of the magnet
50
An induction coil is generally used to
A
rectify an alternating current
B
produce a large input voltage
C
smoothen a pulsating direct current
D
modulate an incoming signal
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