2015 - WAEC Physics Past Questions and Answers - page 4
31
Red light travels faster than blue light when both of them pass through a glass prism because the
A
refractive index of red light is grester than that of blue light
B
refractive index of blue light is greater than that of red light
C
red light is more intense than the blue light
D
blue light is more intense than the red light
correct option: d
Users' Answers & Comments32
An object is placed 20cm from a concave mirror of focal length 15cm. Calculate the linear magnification of the image formed
A
0.5
B
1.5
C
2.0
D
3.0
correct option: d
\(\frac{1}{U} + \frac{1}{V} = \frac{1}{F}\)
\(\frac{1}{V} = \frac{1}{F} - \frac{1}{U}\)
\(\frac{1}{V} = \frac{1}{15} - \frac{1}{20}\)
\(\frac{1}{V} = \frac{\text{4 - 3}}{60}\)
\(\frac{1}{V} = \frac{1}{60}\)
V = 60cm
M = \(\frac{V}{U} = \frac{60}{20}\)
M = 3.0cm
33
All electromagnetic waves in a vacuum have the same
A
wavelength
B
frequency
C
speed
D
amplitude
correct option: c
Users' Answers & Comments34
The diagram given illustrates two charged particles W and X. The charges on W and x are respectively
A
negative; negative
B
negative; positive
C
positive; positive
D
positive; negative
correct option: a
Users' Answers & Comments35
An alternating current supply is connected to an electric lamp which lights with the same brightness as it does with direct current source emf 6v. The peak potential difference of the a.c supply is
A
4.6v
B
6.0v
C
8.5v
D
12.0v
correct option: c
Vo = V\(\_{rms}\) x \(\sqrt{2}\)
Vo = 6 x 1.414
Vo = 8.484
= 8.5v
Users' Answers & CommentsVo = 6 x 1.414
Vo = 8.484
= 8.5v
36
An electric generator rated 12 kW, 2 kV distribute power through a cable of resistance 20\(\Omega\). Calculate the power loss in the cable.
A
120 w
B
360 w
C
720 w
D
2400 w
correct option: c
Power - IV
I = \(\frac{P}{V}\)
= \(\frac{12000}{2000}\)
I = 6A
Power loss = I\(^2\)R = 6\(^2\) x 20
= 720 W
37
Which of the following statements is correct? When capacitors of different values are connected in series
A
the same charge flows through them
B
the same voltage appears across each capacitor
C
different quantities of charges flow through them in different voltages across them
D
different quantities of charges flows through them with the same voltage across them
correct option: a
Users' Answers & Comments38
Which of the following statements about a three-pin plug is/are correct. i. The brown wire is the live wire. ii. The fuse is connected to the live wire. iii. The earth wire is coloured blue
A
i only
B
ii only
C
i and ii only
D
i, ii and iii
correct option: c
Users' Answers & Comments39
The symbol illustrated above is that of a resistor
A
which absorb light
B
which emits light
C
which absorbs heat to function properly
D
whose resistance is light dependent
correct option: c
Users' Answers & Comments40
A wire of cross-sectional area 0.60mm2 has a restivity of 7.2 x 10-7 \(\Omega\). Calculate the length of wire that will have a resistance of 3\(\Omega\).
A
0.25m
B
2.50m
C
3.60m
D
36.00
correct option: b
R = \(\frac{PL}{A}\)
C = \(\frac{RA}{P}\)
C = \(\frac{0.60 \times 10^{-6} \times 3}{7.2 \times 10^{-7}}\)
C = 2.50m
Users' Answers & CommentsC = \(\frac{RA}{P}\)
C = \(\frac{0.60 \times 10^{-6} \times 3}{7.2 \times 10^{-7}}\)
C = 2.50m