2010 - WAEC Physics Past Questions and Answers - page 4

31
Which of the following electromagnetic wave has the longest wavelength?
A
radio-waves
B
gamma rays
C
infrared waves
D
ultraviolet rays
correct option: a
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32
The amplitude of a sound wave determines its
A
frequency
B
quality
C
loudness
D
pitch
correct option: c
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33
As the air column of length L in an air pipe decreases, the frequency of the sationary wave emitted
A
decreases
B
increases
C
varies as L2
D
varies as \(\sqrt{L}\)
correct option: a
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34
A positively charged glass rod is placed near the cap of a positively charged electroscope. The divergence of the leaf is observed to
A
decrease
B
increase
C
remain the same
D
increase and collapse immediately
correct option: b
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35
Capacitors are used in the following devices, except
A
water pumping machines
B
ceiling fans
C
electric irons
D
television sets
correct option: c
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36
Use the diagram above to calculate the current, I.
A
0.60A
B
0.97A
C
1.03A
D
5.00A
correct option: b
\(\frac{1}{R} = \frac{1}{R_1} + \frac{1}{R_2}\)

= \(\frac{1}{6} + \frac{1}{4}\)

R = \(\frac{12}{5} = 2.5\Omega\)

R = 2.4 + 10 = 12.4

V = IR

I = \(\frac{v}{R} = \frac{12}{12.4} = 0.97\)
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37
Determine the potential difference. V across the parallel resistors
A
2.0V
B
2.3V
C
3.0V
D
0.7V
correct option: b
V = IR

= 0.97 x 2.4 = 2.3V
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38
A galvanometer of internal resistance 50\(\Omega\) and full scale deflection of 20 mA is converted into a voltmeter by connecting a resistor of resistance 1950\(\Omega\) in series to it. Calculate the maximum voltage that can be read by the voltmeter
A
20V
B
30V
C
38V
D
40V
correct option: d
V = IR1 + IR2

= 0.02 x 50 + 0.02 x 1950 = 40V
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39
In the wiring of houses, the fuse is connected to the wire coloured
A
blue
B
brown
C
yellow
D
yellow and green
correct option: b
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40
Which of the following factors does not affect the electric resistance of wire?
A
length
B
mass
C
temperature
D
cross-sectional area
correct option: b
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