2022 - JAMB Physics Past Questions and Answers - page 4
The amount of energy required to change a kilogram of ice block into the water without a change in temperature is?
specific latent heat of fusion of ice
specific heat capacity of ice
heat capacity of ice
specific heat of vaporization of ice
Specific latent heat of fusion of a substance is the quantity of heat required to convert the unit mass of the substance from the solid to the liquid state without a change in temperature.
Which expression gives the magnetic flux?
qVB sin\(\theta\)
\(\frac{\mu \phi I}{2 \pi r}\)
BA cos \(\theta\)
-N \(\frac{d \phi}{dt}\)
Magnetic flux is a measurement of the total magnetic field which passes through a given area.
Mathematically, it is the surface integral of the normal component of the magnetic field (B) passing through that surface.
Magnetic force is often denoted Φ or ΦB, with the SI unit Weber
B = Φ/A
Where:
B is magnetic flux density in teslas (T)
Φ is magnetic flux in webers (Wb)
A is area in square meters (m2).
The graph of pressure (P) against the reciprocal of the volume (I/V) in Boyles's law is a___?
hyperbola
parabola
curve
straight line
The graph of pressure (P) against the reciprocal of the volume (I/V) is a straight line passing through the origin.
What is the quantity of heat required to convert 20 g of ice at 0 ºC to water at the same temperature? (Specific latent heat of ice = 336 Jg\(^{-1}\))
7.06 x 10\(^{3}\)J
5.38 x 10\(^{3}\)J
6.72 x 10\(^{3}\)J
1.35 x 10\(^{3}\)J
Quantity of heat = mass * specific latent heat
=> 20 * 336
Quantity of heat = 6720j
= 6.72 x 10\(^{3}\)J
A train of mass 1600kg attains a speed of 25ms\(^{-1}\) in 20 seconds. The power developed in the engine is?
2.5 KW
80 KW
25 KW
50 KW
Let:
force = f
mass = m
acceleration = a
velocity = v
time = t
Force = m * a → m * \(\frac{Δv}{t}\)
Power = f * v
P = m * \(\frac{v}{t}\) * v = m * \(\frac{v^2}{t}\)
p = \(\frac{1600 * 25^2}{20}\)
p = 50,000 or 50 KW
The main factor which affects the speed of sound wave is the?
properties of the medium
amplitude of the sound wave
intensity of the sound wave
loudness of the sound wave
Factors affecting the speed of sound include:
- Nature of material/medium: Sound travels faster in liquids than in gases and faster in solids than in liquids.
- The density of the medium: Sound requires a medium to travel. The density of the medium is among the factors which affect the speed of sound.
- The temperature of the medium: Higher the temperature, the higher the speed of sound in the medium.
A semiconductor is formed by?
co-ordinate bonds
electrovalent bonds
a substance free of bonds
covalent bonds
Semiconductors are generally formed from silicon, germanium, or other pure elements, by adding impurities to the element.
Which of the following is a scalar quantity?
weight
momentum
potential energy
displacement
Vector quantities have magnitude and direction. Scalar quantities have only a magnitude.
Examples of vector quantities:
- weight
- displacement
- acceleration
- force
- momentum
Examples of scalar quantities:
- distance
- mass
- speed
- energy
- time
- volume
The mercury column in the barometer at natural atmospheric pressure has a height of?
0.76 cm at see level
760 cm at sea level
7.6 cm at sea level
76 cm at sea level
If an object just begins to slide on a surface inclined at 30º to the horizontal,the coefficient of friction is?
√3
\(\frac{√3}{2}\)
\(\frac{1}{√2}\)
\(\frac{1}{√3}\)
A body sliding down a plane inclined at 30º to the horizontal has coefficient of friction = tan 30º
=> \(\frac{1}{√3}\)