2014 - JAMB Physics Past Questions and Answers - page 3
21
Heat transfer by convection in a liquid is due to the
A
Latent heat of vaporization of the liquid
B
Increased vibration of the molecules of the liquid about theit mean position
C
Variation of density of the liquid
D
Expansion of the liquid as it is heated
correct option: d
Users' Answers & Comments22
The distance between two successive crests of a wave is 15cm and the velocity 300ms-1. Calculate the frequency.
A
2.0x102Hz
B
4.5x103Hz
C
2.0x103Hz
D
4.5x102Hz
correct option: c
Wavelength = 15cm = 0.15m
Velocity = 300m/s
V = fx
F = V/Wavelength
F = 300/0.15 Hertz
F = 2 x 103Hz
Users' Answers & CommentsVelocity = 300m/s
V = fx
F = V/Wavelength
F = 300/0.15 Hertz
F = 2 x 103Hz
23
A boy receives the echo of his clap reflected by a nearby hill 0.8s later. How far is he from the hill?
A
528m
B
66m
C
136m
D
264m
correct option: c
Time for echo both ways = 0.8
Therefore time for echo in 1 way = 0.8/2 = 0.4
Distance = Speed x time
Distance = 340 x 0.4
Distance = 136m
Users' Answers & CommentsTherefore time for echo in 1 way = 0.8/2 = 0.4
Distance = Speed x time
Distance = 340 x 0.4
Distance = 136m
24
An object is placed 10m from a pinhole camera of length 25cm. Calculate the linear magnification.
A
2.5x102
B
2.5x10-2
C
2.5x10-1
D
2.5x101
correct option: b
\(\text{Linear Magnification} = \frac{\text{Length of Camera}}{\text{Distance of the Object}}\)
\(\text{Linear Magnification} = \frac{25}{1000}\)
\(\text{Linear Magnification} = 2.5 \times 10^{-2}\)
Users' Answers & Comments\(\text{Linear Magnification} = \frac{25}{1000}\)
\(\text{Linear Magnification} = 2.5 \times 10^{-2}\)
25
The focal length of a concave mirror is 2.0cm. If an object is placed 8.0cm from it, the image is at
A
2.7m
B
2.0m
C
2.3m
D
2.5m
correct option: a
\(\frac{1}{U} + \frac{1}{V} = \frac{1}{f}\)
\(\frac{1}{8} + \frac{1}{V} = \frac{1}{2}\)
\(V = \frac{8}{3}\)
\(V = 2.7cm\)
Users' Answers & Comments\(\frac{1}{8} + \frac{1}{V} = \frac{1}{2}\)
\(V = \frac{8}{3}\)
\(V = 2.7cm\)
26
In a compound microscope, the objective and the eye piece focal lengths are
A
At infinity
B
Long
C
Short
D
The same
correct option: c
Users' Answers & Comments27
When a telescope is in normal use, the final image is at
A
Infinity
B
The focus
C
The radius of curvature
D
The near point
correct option: a
Users' Answers & Comments28
When a negatively charged rod is brought near the cap of a charged gold leaf electroscope which has positive charges, the leaf
A
Remains the same
B
Collapses
C
Collapses and diverges again
D
Diverges
correct option: b
Users' Answers & Comments29
What charge is stored in a 0.1F capacitor when a 10V supply is connected across it?
A
1C
B
5C
C
4C
D
2C
30
The maximum power transfer occur in a cell when the external resistance is
A
Twice the internal resistance of the cell
B
The same as the internal resistance of the cell
C
Greater than the internal resistance of the cell
D
Less than the internal resistance of the cell
correct option: b
Users' Answers & Comments