2019 - JAMB Physics Past Questions and Answers - page 8
In the molecular explanation, heat is transferred by the
free electrons
free atoms
free molecules
free solids
Conduction is as a result of free electrons
Convection as a result of the movement of the fluid involved
Radiation as a result of electromagnetic waves.
Which of these is observed when air is pumped out of a discharge tube without lowering its pressure
the conductivity of the air increases
the conductivity of the air decreases
conduction does not occur
spark are produced
Which of the following characteristics of a wave is used in the measurement of the depth of the Sea?
diffraction
interference
refraction
reflection
Sea depth can be measured using the echo reflected in sound waves.
If the attraction of the sun is suddenly ceased, the earth would continue to move in a straight line making a tangent with the original orbit. This statement is derived from Neutron's
First law of motion
Second law of motion
Third law of motion
Law of universal gravitation
Newton's First law of motion states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force
Heat may be transferred by conduction, convention and radiation. By which of these methods does heat travel through vacuum?
Conduction only
Convection only
Radiation only
All these methods
The part of the human eye that does similar work as the diaphragm of a camera lens is the
Ciliary muscles
Pupil
Iris
Retina
Workdone on an object to bring it to a certain point in space is called
Gravitational potential energy
Potential energy
Kinetic energy
Mechanical energy
Gravitational energy is the potential energy a physical object with mass has in relation to another massive object due to gravity. It is potential energy associated with the gravitational field. Gravitational energy is dependent on the masses of two bodies, their distance apart and the gravitational constant. Wikipedia
A copper rod, 5m long when heated through 20c, expands by 1mm. If a second copper rod, 2.5m long is heated through 5c, by how much will it expand?
4mm
A. 2mm
B. 0.25mm
0.12mm
l\(_1\) = 5m, ΔT = 10c, l\(_2\) - l\(_1\) = 1mm
l\(_1\) = 2.5m, ΔT = 5c, l\(_2\) - l\(_1\) = ?
| α = | l\(_2\) - l\(_1\)
l\(_1\)ΔT |
| 1
5(10) |
= | l\(_2\) - l\(_1\)
2.5(5) |
| l\(_2\) | - | l\(_2\) | = | 2.5(5)
5(10) |
= | 1
4 |
= | 0.25mm |
A safety precaution designed to prolong the life of a lead acid accumulator is
By topping up the cells with concentrated acid
The use of naked flame when charging the battery
Keeping the specific gravity of the electrolyte within specified range
By connecting wires to the terminals directly when testing the level of charging
The mass of water vapour in a given volume of air is 0.05g at 20°C, while the mass of water vapour required to saturate it at the same temperature is 0.15g. Calculate the relative humidity of the air.
3.33%
5.55%
33.33%
55.55%
| RH | = | mass of water vapour in volume of air
mass of water vapour for saturation |
| RH | = | m
M |
= | 0.05
0.15 |
× | 100 | = | 5
0.15 |
= | 500
15 |
= | 33.33% |
RH = 33.33%