2016 - WAEC Physics Past Questions and Answers - page 4
31
An astronomical telescope has objectives and eye-piece lenses of focal length 3.5m and 5cm respectively. Determine the magnifying power of the telescope when in normal adjustment
A
70.0
B
17.5
C
7.0
D
0.7
correct option: a
Magnify power = \(\frac{f_o}{f_e}\)
= \(\frac{3.5 \times 100}{5.0}\)
= 70
Users' Answers & Comments= \(\frac{3.5 \times 100}{5.0}\)
= 70
32
An aluminium cable of diameter 4 x 10-3m and resistivity 3.0 x 10-8\(\omega\)m has a resistance of 21\(\Omega\). Calculate the length of the cable. (\(\pi = 3.14\))
A
8.0 x 102m
B
8.8 x 103m
C
8.0 x 104m
D
8.8 x 104m
correct option: b
R = \(\frac{4eL}{\pid^2}\)
L = \(\frac{R\pid^2}{4e}\)
= \(\frac{21 \times 3.14(4 \times 10^{-3})^2}{4 \times 3.0 x 10^{-8}}\)
= 8.8 x 103m
Users' Answers & CommentsL = \(\frac{R\pid^2}{4e}\)
= \(\frac{21 \times 3.14(4 \times 10^{-3})^2}{4 \times 3.0 x 10^{-8}}\)
= 8.8 x 103m
33
The electricity meters in houses measure energy unit consumed in
A
kilowatt-hour
B
volt
C
ampere
D
coulomb
correct option: a
Users' Answers & Comments34
A man and his friend have masses 70kg and 60kg respectively. If they are seated 1.0m apart, calculate the gravitational force of attraction between them. (G = 6.67 x 10-11 Nm2 kg-2)
A
1.59 x 10-14 N
B
2.80 x 10-7 N
C
1.30 x 10-2 N
D
6.30 x 1013 N
correct option: b
F = \(\frac{GM_1M_}{r^2}\)
= \(\6.67 \times 10^{-11} \times 70 \times 60}{1^2}\)
= 2.8014 x 10-7 N
Users' Answers & Comments= \(\6.67 \times 10^{-11} \times 70 \times 60}{1^2}\)
= 2.8014 x 10-7 N
35
The p.d across a parallel-plate capacitor is 103V. If the distance between the two plates is 10cm. Calculate the magnitude of the electric field strength between the plates.
A
1.0 x 104Vm-1
B
1.0 x 105Vm-1
C
1.5 x 105Vm-1
D
2.0 x 105Vm-1
correct option: a
E = \(\frac{v}{d} = \frac{10^3}{0.1}\)
= 10000
= 1.0 x 104Vm-1
Users' Answers & Comments= 10000
= 1.0 x 104Vm-1
36
Two different materials, rubbed against each other acquired opposite charges when separated. This is an example of charging by
A
induction
B
friction
C
conduction
D
convection
correct option: b
Users' Answers & Comments37
Two different materials, rubbed against each other acquired opposite charges when separated. This is an example of charging by
A
induction
B
friction
C
conduction
D
convection
correct option: b
Users' Answers & Comments38
Which of the following factors does not affect the e.m.f of a primary cell? Its
A
size
B
internal resistance
C
operating temperature
D
duration of usage
correct option: a
Users' Answers & Comments39
Two magnets are used to magnetize a soft iron bar PQ as illustrated in the diagram given. The correct polarity at P and Q respectively
A
S and N
B
N and N
C
S and S
D
N and S
correct option: b
Users' Answers & Comments40
In storing magnets, keepers are used to
A
reduced self-demagnetization
B
cancel the effect of the earth's magnetic field
C
protect the magnet from stray electric field
D
increase the strangth of the magnets
correct option: a
Users' Answers & Comments