What is the unit of electric charge?
The SI unit of electric charge is the coulomb (C), defined as the charge transported by 1 ampere in 1 second.
Which of the following dimensions represents impulse?
Impulse = force × time = (MLT⁻²) × T = MLT⁻¹.
A body accelerates uniformly from rest at 2 ms⁻². Calculate its velocity when it has travelled a distance of 9m.
Using v² = u² + 2as, u = 0, a = 2 ms⁻², s = 9 m; v² = 36, v = 6 ms⁻¹.
Which of the following statements about matter is not correct?
Molecules in solids vibrate but do not move freely; liquids and gases have greater molecular freedom.
What is the SI unit of power?
Power is the rate of energy transfer, with SI unit watt (W = J/s).
Two forces 100 N and 60 N act on an object of mass 10 kg. Neglecting friction, calculate the acceleration of the object.
Assuming forces in the same direction, net force = 160 N; a = F/m = 160/10 = 16 ms⁻².
A body weighing 14 N in air is partially immersed in water. If the mass of water displaced in the process is 200 g, calculate the upthrust on the body. [g = 10 ms⁻²]
Upthrust = weight of displaced water = 0.2 kg × 10 ms⁻² = 2 N. (Option C fixed to avoid repetition.)
Which of the following processes is not surface phenomenon?
Photo emission involves light ejecting electrons from metal surfaces, but it is not exclusively a surface tension-related phenomenon like the others.
A chemical balance is used for measuring
A chemical balance measures mass precisely for analytical purposes.
A body is whirled round a circular path at constant speed. The velocity is tangential to the path while the centripetal acceleration is towards the center.
Velocity is tangential (along the path), acceleration is radial (perpendicular to velocity, towards center). (Question rephrased to avoid diagram dependency.)
A motorist travelling at 72kmh⁻¹ had his eyes shut for 0.4s during a hard sneeze. Calculate the distance covered by him during this time interval
Speed = 72 km/h = 20 m/s; distance = speed × time = 20 × 0.4 = 8 m.
The angle at which a projectile must be fired to cover maximum range is
Maximum range for a projectile on level ground occurs at θ = 45°, where sin(2θ) = 1.
A body can undergo the following types of motion except
Random is not a standard classification of motion; rotational, translational, and relative are recognized types.
A stone is thrown horizontally with a speed of 10 m/s from the top of a cliff 20 m high. How far from the base of the cliff does the stone land? [Take g = 10 m/s²]
The time to fall is found from h = (1/2)gt², so 20 = 5t², t² = 4, t = 2 s. Horizontal distance = speed × time = 10 × 2 = 20 m.
The energy stored in a spring of stiffness constant k = 2000 Nm⁻¹ when extended by 4cm is
Elastic potential energy = (1/2)kx² = 0.5 × 2000 × (0.04)² = 1.6 J.
A resistor of 20 Ω carries a current of 2 A. What is the potential difference across it?
By Ohm's law, V = IR = 20 Ω × 2 A = 40 V. This is the voltage drop across the resistor.
A plane is inclined at an angle to the horizontal. Its velocity ratio is
Velocity ratio for inclined plane = 1 / sin θ.
The reason bubbles get bigger in size as they rise in a heated beaker of water is
As bubbles rise, pressure decreases, causing expansion by Boyle's law; heating aids but pressure is key.
Which of the following devices transforms light energy to electrical energy?
Solar cells (photovoltaic cells) convert light directly to electricity via the photoelectric effect.
A motor of a corn mill machine operates on electrical energy of 1.44 x 10⁵. If one-quarter of the energy is wasted in the form of sound and heat, determine the efficiency of the machine.
Useful energy = 3/4 of total = 75%; efficiency = (useful / total) × 100% = 75%.
Thermal energy added or removed from a substance that changes the state of the substance is called
Latent heat is the energy absorbed or released during phase change without temperature change.
The maximum density of water occurs at a temperature of
Water has anomalous expansion; density peaks at 4°C due to hydrogen bonding structure.
The inverse of the time required for a wave to complete one full cycle is called
Frequency f = 1 / T, where T is the period (time for one cycle).
Two bar magnets are placed near each other. Which of the following correctly illustrates the magnetic field pattern formed by the pair?
Like poles repel, unlike attract; field lines form closed loops, appearing circular around magnets.
The force per unit charge experienced at a point in a field is the
Electric field strength E = F/q, force per unit charge.
Which of the following object is not a conductor of electricity?
Dry wood is an insulator; the others conduct due to free electrons or ions.
A circuit is set up with a 30V battery and three 10Ω resistors in series. When the key is closed, the reading on the ammeter will be
Total R = 30 Ω; I = V/R = 30/30 = 1 A.
Which of the following statements is/are correct? I. Gravitational potential due to a mass at a point a distance r away is proportional to r² II. Gravitational field strength is a scalar quantity III. Gravitational intensity is proportional to the weight of a unit mass
I false (∝ 1/r), II false (vector), III true (g = weight/mass). (Options fixed: B to I and III, C to III only, D to II only.)
The text below illustrate electrical connections to the element of an electric pressing iron. In which of the connections is the fuse correctly fixed?
Fuse is placed before the element in series to protect the circuit from overload.
A transformer connected to a 240 Vrms has 3000 turns in its primary coil and 500 turns in its secondary coil. Calculate the output voltage.
V_s / V_p = N_s / N_p; V_s = 240 × (500/3000) = 40 V.
A lamp rated 100 W, 240V is lit for 5 hours. Calculate the cost of lighting the lamp if 1 kWh of electrical energy cost ₦5.
Energy consumed = power × time = 100 W × 5 h = 500 Wh = 0.5 kWh. Cost = 0.5 kWh × ₦5/kWh = ₦2.50.
Calculate the heat required to raise the temperature of 500 g of water from 20°C to 80°C. [Specific heat capacity of water = 4200 J kg⁻¹ K⁻¹]
Q = mcΔθ = 0.5 kg × 4200 J kg⁻¹ K⁻¹ × 60 K = 126000 J = 126 kJ. This is the energy needed for the temperature change.
The main reason why a.c. is transmitted at very high voltage and low current is that it
Power loss = I²R; high V, low I for same power reduces loss in transmission lines.
A sound wave travels at 340 m/s in air and has a wavelength of 0.68 m. What is its frequency?
Frequency f = v / λ = 340 m/s / 0.68 m = 500 Hz. This relates the speed, wavelength, and frequency of the wave.
The opposition offered to an alternating current in a C - R series circuit is known as
In CR circuit, total opposition is impedance Z = sqrt(R² + (1/ωC)²).
Which of the following pairs of concepts constitutes complementary variables as expressed by the Heisenberg uncertainty principle?
Heisenberg uncertainty principle: Δx · Δp ≥ ħ/2, position and momentum are complementary.
The nucleon number of an atom is the total number of
Nucleon number (A) = protons + neutrons in the nucleus.
An object is placed 20 cm in front of a converging lens of focal length 10 cm. What is the image distance?
Using the lens formula 1/f = 1/v - 1/u, with u = -20 cm, f = +10 cm: 1/v = 1/10 + 1/(-20) = 0.05, v = 20 cm.
Which of the following statements about gamma radiation is correct? Gamma radiation can
Gamma rays are naturally present from cosmic rays and radioactive decay in the environment; they are invisible, penetrate foil, and tracers use beta/alpha more.
A radioactive substance has a half-life of 5 days. What fraction of the substance remains after 10 days?
After one half-life (5 days), 1/2 remains; after two half-lives (10 days), (1/2)² = 1/4 remains. This follows exponential decay.
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