1993 - JAMB Physics Past Questions and Answers - page 3
21
A beam of light is incident from air to water at an angle of 30oC. Find the angle of refraction if the refractive index of water is \(\frac{4}{3}\)
A
15oC
B
18oC
C
22oC
D
24oC
22
The property of the eye known as its power of accommodation is controlled by the
A
pupil
B
virteous humour
C
iris
D
ciliary muscles
correct option: d
Users' Answers & Comments23
Which of the following correctly explain(s) why a green leaf appears green in bright day light? i. it absorbs only the green component of sunlight. ii. it absorbs all colour of sunlight except green. iii. it reflects only the green component of sunlight.
A
i only
B
ii only
C
i and iii only
D
ii and iii only
correct option: d
Users' Answers & Comments24
Which of the following correctly explains why soft iron is proffered to steel in electromagnets? i. soft iron is more readily magnetized than steel. ii. soft iron is more readily demagnetized than steel. iii. soft iron retains magnetism more than steel.
A
i only
B
ii and iii only
C
i and ii only
D
i, ii, and iii.
correct option: c
Users' Answers & Comments25
A current carrying conductor experiences a force when placed in a magnetic field because the
A
conductor is magnetized
B
magnetic field of the current interacts with external magnetic field
C
force is due to the motor principle
D
electric field of the current interacts with the external magnetic field
correct option: b
Users' Answers & Comments26
A simple cell with mercury-amalgamated zinc electrode prevents
A
local actions
B
polarization
C
buckling
D
degradation
correct option: a
Users' Answers & Comments27
The terminal voltage of a battery is 4.0V when supplying a current of 2.0A, and 2.0V when supplying a current of 3.0A. The internal resistance of the battery is
A
0.5 \(\Omega\)
B
1.0\(\Omega\)
C
2.0\(\Omega\)
D
4.0\(\Omega\)
28
A current of 100mA passes through a conductor for 2 minutes. The quantity of electricity transported is
A
200C
B
50C
C
12C
D
0.002C
29
A parallel plate capacitor of area 10cm2 in vacuum has a capacitance of 10-2\(\mu\)F. What is the distance between the plates?(e = 9 x 10-12fm)
A
9 x 10-13m
B
9 x 10-7m
C
9 x 10-3m
D
9 x 107m
correct option: b
C = \(\frac {\varepsilon_o\ A}{d}\)
10-2 x 10-6 = \(\frac {9 \times 10 ^{-12}}{d}\) x 10-4
= 9 x 10-7m
Users' Answers & Comments10-2 x 10-6 = \(\frac {9 \times 10 ^{-12}}{d}\) x 10-4
= 9 x 10-7m
30
A 40-W instrument has a resistance of 90\(\Omega\). On what voltage should it be operated normally?
A
60V
B
150V
C
225V
D
3600V
correct option: a
P = \(\frac{V}{R}\)
V = \(\sqrt{PR}\)
V = \(\sqrt{40 \times 90}\)
= 60V
Users' Answers & CommentsV = \(\sqrt{PR}\)
V = \(\sqrt{40 \times 90}\)
= 60V