2005 - WAEC Physics Past Questions and Answers - page 4
31
In which of the following media is the transmission of sound wave fastest?
A
Vacuum
B
Air
C
Wood
D
Iron
correct option: d
Users' Answers & Comments32
The ability of a material to store an electric charge when its plates are at different potentials is referred to as its
A
conductance
B
inductance
C
capacitance
D
resistance
correct option: c
Users' Answers & Comments33
Two capacitors if capacitance 0.4\(\mu F\) and 0.5\(\mu F\) are connected in parallel and charged to a p.d. of 50V, Determine the total charge acquired
A
45\(\mu C\)
B
25\(\mu C\)
C
20\(\mu C\)
D
10\(\mu C\)
correct option: a
C = (C_1 + C_2) = 0.4 + 0.5 = 0.9(\mu F)
Q = Cv = 0.9 x 50 = 45(\mu C)
34
A parallel plate capacitor of capacitance 600\(\mu F\) has a potential difference of 200V between its plates. Calculate the charge on either plate of the capacitor
A
1.2C
B
3.3C
C
3330.0C
D
12.0000.0C
35
A parallel plate capacitor of capacitance 600\(\mu F\) has a potential difference of 200V between its plates. Calculate the charge on either plate of the capacitor
A
1.2C
B
3.3C
C
3330.0C
D
12.0000.0C
36
a chemical cell of internal resistance 1\(\Omega\) supplies electric current to an external resistor of resistance 3\(\Omega\). Calculate the efficiency of the cell
A
75%
B
50%
C
33%
D
25%
correct option: a
R = (r_1 + R = 1 + 3 = 4\Omega)
(\frac{3}{4} \times \frac{100}{1} = 75)%
37
An electric lamp is rated 240V, 40W. What is the cost of running the lamp for 72 hours if the electricity authority charges N2.50 per kWh?
A
N7.20
B
N18.00
C
180.00
D
N720.00
correct option: a
Cost = (\frac{Pt}{1000}) x cost per kWh
= (\frac{40 \times 72}{1000} \times 2.50 = N7.20)
38
Which of the following statements explains lost volt in an electric circuit? The
A
total p.d from a source to maintain a flow of current through the circuit as well as the source
B
p.d to drive current through the circuit component except the source
C
p.d across all external components connected to the source of electricity
D
p.d across the internal resistance of the cell
correct option: c
Users' Answers & Comments39
A constantan wire has a cross sectional area of 4 x 10-8m2 and a resistivity of 1.1 x 10-6\(\Omega\)m. If a resistor of resistance 11\(\Omega\) is to be made from this wire, calculate the length of the wire required
A
0.4m
B
0.8m
C
2.5m
D
5.0m
correct option: a
L = (\frac{RA}{e} = \frac{11 \times 4 \times 10^{-8}}{1.1 \times 10{-4}} = 0.4m)
Users' Answers & Comments40
The mass and weight of a body on earth are 8kg and 80N respectively. Determine the mass and weight of the body respectively on a planet where the pull of gravity is \(\frac{1}{8}\) that on earth
A
8kg, 8N
B
1kg, 10N
C
64kg, 10N
D
8kg, 10N