2007 - WAEC Physics Past Questions and Answers - page 4
31
A rectangular glass prism of thickness d and absolute refractive index n is placed on a point object which is viewed vertically downward from above the prism. Which of the following expressions correctly defines the apparent upward displacement of the object?
A
\(\frac{d}{n}\)
B
dn
C
\(\frac{d}{n - 2}\)
D
\(\frac{d(n - 1)}{n}\)
correct option: a
n = \(\frac{R.d}{A.d}\)
R.d = \(\frac{R.d}{n} = \frac{d}{n}\)
Users' Answers & CommentsR.d = \(\frac{R.d}{n} = \frac{d}{n}\)
32
Which of the following factors can affect the speed of sound in air? i. The temperature of the surrounding ii. The direction of the wind iii. The pitch of the sound.
A
i and ii only
B
ii and iii only
C
i and iii only
D
i, ii and iii
correct option: a
Users' Answers & Comments33
A sounding tuning fork is brought near the open end of a pipe containing air and the loudness of the sound is observed to increase. This observation is due to
A
an echo
B
resonance
C
interference
D
reverbration
correct option: b
Users' Answers & Comments34
Which of the following statements about sound wave is not correct? Sound waves can be
A
reflected
B
refracted
C
diffracted
D
polarized
correct option: d
Users' Answers & Comments35
A dry plastic comb used in combing hair was found to attract pieces of paper and dust. The most probable explanation for this phenomenon is that the comb has been given
A
magnetization by induction
B
electric charges by induction
C
electric charges by conduction
D
electric charges by friction
correct option: d
Users' Answers & Comments36
Which of the following statements is correct about resonance? Resonance occurs when a body
A
vibrates with its natural frequency
B
is forced to vibrate on its own natural frequency by another body at the same vibration
C
vibrates at the frquency of the body causing the vibration
D
vibrates with an irregular frequency
correct option: c
Users' Answers & Comments37
Which of the following components is used for storing electric charges?
A
inductor
B
resistor
C
capacitor
D
electrometer
correct option: c
Users' Answers & Comments38
Which of the following operations does not represent an action of a force field?
A
falling of a mango fruit from the tree
B
picking of nails using a bar magnet
C
repulsion of two like charges
D
pushing of a wheel-barrow on a level gound
correct option: d
Users' Answers & Comments39
A bulb marked 240V, 40W is used for 30 minutes. Calculate the heat generated
A
320J
B
400J
C
10800J
D
72000J
40
Five 80-W and three 100W are run for 8 hours. If the cost of energy is N5.00 per unit, calculate the cost of running the lamp. [1 unit = 1 kWh]
A
N280.00
B
N28.00
C
N7.20
D
N1.44
correct option: b
P = (80 x 5 + 100 x 3)8
= 5600W
Cost = \(\frac{5600}{1000} \times 5 = N28\)
Users' Answers & Comments= 5600W
Cost = \(\frac{5600}{1000} \times 5 = N28\)