1991 - JAMB Physics Past Questions and Answers - page 3
21
Which of the following is TRUE of light and sound waves?
A
they both transmit energy
B
they both need a mediumfor propagation
C
they are both transverse waves
D
their velocities in air are equal
correct option: a
Users' Answers & Comments22
The image in a pin-hole camera is
A
errect and formed by refraction through a lens
B
virtual and formed by dispersion
C
erect and gets sharper as the hole becomes larger
D
inverted and formed by the light from each point travelling in a straight line
correct option: d
Users' Answers & Comments23
When a plane mirror at which a ray is incident is rotated through an angle \( \theta \), the reflected ray will be rotated through
A
\(\frac{1}{2}\)\(\theta\)
B
\(\theta\)
C
2\(\theta\)
D
3\(\theta\)
correct option: c
Users' Answers & Comments24
A trough 12.0cm deep is filled with water of refractive index \(\frac{4}{3}\). By how much would a coin at the bottom of the trough appear to be displaced when viewed vertically from above the water surface?
A
3.0cm
B
6.0cm
C
9.0cm
D
16.0cm
correct option: a
\(\frac{4}{3}\) = \(\frac{12}{\text {Apparent depth}}\)
Apparent depth = 9cm
Height by which coin is raised = 12 - 9
= 3cm
Users' Answers & CommentsApparent depth = 9cm
Height by which coin is raised = 12 - 9
= 3cm
25
In a ray diagram for a thin converging lens, a ray that is not parallel to the optic axis but passes through the optic center will
A
pass through undeviated
B
pass through the center of curvature after refraction
C
emerge parallel to the principal axis
D
pass through the principal focus after refraction
correct option: a
Users' Answers & Comments26
Which of the following correctly, describes the image of an object, 4cm from a diverging lens of focal length 12cm?
A
The image is virtual, 3cm in front of the lens
B
The image is real, 6cm behind the lens
C
The image is virtual, 6cm in front of the lens
D
The image is real, 3cm in front the lens
correct option: a
F = \(\frac{uv}{u + v}\)
F = -ve
-12 = \(\frac{4 \times v}{4 + v}\)
v = -3cm
Users' Answers & CommentsF = -ve
-12 = \(\frac{4 \times v}{4 + v}\)
v = -3cm
27
Two tuning forks of frequency 256Hz and 260Hz are sounded close to each other. What is the frequency of the beats produced?
A
2Hz
B
4Hz
C
8Hz
D
258Hz
28
A man hears his echo from a nearby hill 2s after he shouted. If the frequency of his voice is 260Hz and the wavelength is 1.29m, how far away is the hill?
A
330.0m
B
335.4m
C
660.0m
D
670.8m
correct option: b
v = \(\lambda\)F
260 x 1.29 =335.4ms-1
Echo time = \(\frac{2}{2}\) = 1sec.
distance = v x t
= 335.4 x 1 = 335.4m
Users' Answers & Comments260 x 1.29 =335.4ms-1
Echo time = \(\frac{2}{2}\) = 1sec.
distance = v x t
= 335.4 x 1 = 335.4m
29
When the bottom tip of a vibrating tuning fork is held in contact with a wooden box, a louder sound is heard. This phenomenon is known as
A
beats
B
echoing
C
resonance
D
reverberation
correct option: c
Users' Answers & Comments30
Which of the following statements is CORRECT about the earth's magnetic field?
A
the angle of dip is the angle which a freely suspended magnet makes with the vertical
B
the angle of declination is the angle between the magnetic meridian and the geographic meridian
C
the angle of declination is the angle which a magnetic compass makes with the magnetic meridian
D
the angle of inclination is the difference between the angle of dip and the angle of declination
correct option: b
Users' Answers & Comments