2019 - JAMB Physics Past Questions and Answers - page 7
In which of the points labelled A, B, C, D and E on the conductor shown would electric charge tend to concentrate most
A
B
C
E
Charge concentration is higher are at the pointed ends or places with a high-density point.
The point at which the molecules of a loaded wire begin to slide across each other resulting in a rapid increase in extension is
yield point
proportionality point
deformation point
elastic point
the elastic limit of a material is the greatest stress that can be applied to it without causing plastic (permanent) deformation. This represents a particular load beyond which stretched material does not completely recover its original shape & size.
The resultant capacitance in the figure shown is
0.4μf
0.8μf
1.8μf
4.5μf
In a parallel arrangement: 2 + 4 = 6μf
| in a series arrangement: | 1
C\(_T\) |
= | 1
2 |
+ | 1
3 |
+ | 1
6 |
+ | 1
4 |
| 1
C\(_T\) |
= | 15
12 |
| C\(_T\) | = | 12
15 |
= | 0.8μf |
The lower fixed part of a faulty thermometer reads 2°C while the upper fixed point is 100°C.
What is the true temperature when the thermometer reads 51°C?
52°C
50°C
49°C
46°C
C\(_{\theta}\) = 50, C\(_0\) = 2, C\(_{100}\) = 100
| θ = | C\(_{\theta}\) - C\(_0\)
C\(_{100}\) - C\(_0\) |
× | 100 | = | 51 - 2
100 - 2 |
× | 100 |
| = | 49
98 |
× | 100 |
θ = 50°C
If a body moves with a constant speed and at the same time undergoes an acceleration, its motion is said to be
A coil X is moved quickly away from the end Y of a stationary metal bar and a current then flows in X as shown above.
Then
the bar is not a magnet
Y is a north pole
Y is a South pole
Y repels coil X
Moving the N - S magnet towards a coil clockwise direction of current in the coil is equivalent to a coil moved away from S-N, Y - North pole
A boy pushes a 500kg box along a floor with a force of 2000N. If the velocity of the box is uniform, the co-efficient of friction between the box and the floor is
1
A. 0.8
0.65
0.4
m = 500kg,
W = mg = 500 × 10 = 5000N
F = 2000N
| μ = | Force at constant velocity
weight |
= | 2000
5000 |
= 0.4 |
μ 0.4
The following are some units
I. Ns
II. Non
III. Nm\(^{-2}\)
IV. J°K\(^{-1}\)
V. JKj\(^{-1}\)
What are the units of latent heat?
I
II
III
V
Latent heat or specific latent heat = L
| Heat(energy) H = | mL | => | L | = | H
m |
= | energy
mass |
When two objects A and B are supplied with the same quantity of heat, the temperature change in A is obtained to be twice that of B. The mass of P is half that of Q. The ratio of the specific heat capacity of A to B is
1 : 4
4 : 1
1 : 1
2 : 1
θA = 2θ\(_{B}\),
| m\(_A\) | = | 1
2 |
m\(_B\) |
H = MCθ
m\(_A\)c\(_A\)θ\(_A\) = m\(_B\)c\(_B\)θ\(_B\)
( 1/2 m\(_B\))C\(_A\) (2θ\(_B\)) = m\(_B\)c\(_B\)θ\(_B\)
| C\(_A\)
C\(_B\) |
= | 1
1 |
The ratio is 1 : 1
The volume of 0.354g of helium at 273°C and 114cm of mercury pressure is 2667cm\(^3\). Calculate the volume
2000.25 cm\(^3\)
200.025 cm\(^3\)
4003.27 cm\(^3\)
2010.25 cm\(^3\)
m = 0.354g,
T\(_1\) = 273°C = 273 + 273 = 576K
P\(_1\) = 114cmHg, V\(_1\) = 2667cm\(^3\) at STP
T\(^2\) = 273K, P\(_2\) = 76cmHg, V\(_2\) = ?
But,
| P\(^1\)V\(^1\)
T\(^1\) |
= | P\(^2\)V\(^2\)
T\(^1\) |
| V\(_2\) | = | 114 × 2667 × 273
76 × 576 |
= | 2000.25cm\(^3\) |