Physics
Q. If a 5Ω resistor is connected to a 10V source, what is the power dissipated? (2023)
A.
2W
B.
5W
C.
10W
D.
20W
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Solution
Power P = V²/R = (10V)² / 5Ω = 100 / 5 = 20W.
Correct Answer: C — 10W
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Q. If a 6Ω resistor is connected in parallel with a 3Ω resistor, what is the equivalent resistance? (2023)
A.
2Ω
B.
1.5Ω
C.
4Ω
D.
9Ω
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Solution
Using the formula 1/R_eq = 1/R1 + 1/R2, we get 1/R_eq = 1/6 + 1/3 = 1/6 + 2/6 = 3/6, thus R_eq = 2Ω.
Correct Answer: A — 2Ω
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Q. If a 9V battery is connected to a 3Ω resistor, what is the current flowing through it? (2021)
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Solution
Using Ohm's law, I = V/R = 9V / 3Ω = 3A.
Correct Answer: B — 2A
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Q. If a capacitor is charged to 12V and has a capacitance of 6μF, what is the stored energy? (2022)
A.
0.432 mJ
B.
0.072 mJ
C.
0.864 mJ
D.
0.216 mJ
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Solution
Energy = 0.5 × C × V² = 0.5 × 6 × 10^-6 × 12² = 0.432 mJ.
Correct Answer: A — 0.432 mJ
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Q. If a car accelerates from rest to a speed of 20 m/s, and its mass is 1000 kg, what is the kinetic energy of the car at that speed? (2020)
A.
200 J
B.
1000 J
C.
2000 J
D.
4000 J
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Solution
Kinetic Energy = 0.5 × mass × velocity² = 0.5 × 1000 kg × (20 m/s)² = 200000 J = 2000 J
Correct Answer: C — 2000 J
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Q. If a car accelerates from rest to a speed of 20 m/s, what is the kinetic energy of the car if its mass is 1000 kg?
A.
200,000 J
B.
100,000 J
C.
50,000 J
D.
400,000 J
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Solution
Kinetic Energy = 0.5 × mass × velocity² = 0.5 × 1000 kg × (20 m/s)² = 200,000 J
Correct Answer: B — 100,000 J
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Q. If a car travels at a speed of 60 km/h, how far will it travel in 2 hours? (2022)
A.
120 km
B.
100 km
C.
150 km
D.
90 km
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Solution
Distance = Speed × Time = 60 km/h × 2 h = 120 km.
Correct Answer: A — 120 km
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Q. If a car with a mass of 1200 kg is moving at a speed of 15 m/s, what is its kinetic energy? (2021)
A.
13500 J
B.
9000 J
C.
18000 J
D.
27000 J
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Solution
Kinetic Energy = 0.5 × mass × velocity² = 0.5 × 1200 kg × (15 m/s)² = 13500 J
Correct Answer: A — 13500 J
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Q. If a circuit has a resistance of 5 ohms and a current of 2 A, what is the voltage? (2014)
A.
10 V
B.
5 V
C.
2 V
D.
1 V
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Solution
Using Ohm's Law, V = I × R = 2 A × 5 Ω = 10 V.
Correct Answer: A — 10 V
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Q. If a circuit has a total resistance of 12Ω and a current of 1.5A, what is the voltage across the circuit? (2021)
A.
18V
B.
12V
C.
15V
D.
10V
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Solution
Using Ohm's law, V = IR = 1.5A * 12Ω = 18V.
Correct Answer: A — 18V
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Q. If a circuit has a total resistance of 12Ω and a current of 3A flows through it, what is the voltage across the circuit? (2020)
A.
36V
B.
12V
C.
4V
D.
24V
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Solution
Using Ohm's law, V = IR = 3A * 12Ω = 36V.
Correct Answer: A — 36V
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Q. If a circuit has a total resistance of 12Ω and a current of 4A, what is the voltage across the circuit? (2023)
A.
48V
B.
36V
C.
24V
D.
12V
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Solution
Using Ohm's law, V = IR = 4A * 12Ω = 48V.
Correct Answer: A — 48V
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Q. If a circuit has a total resistance of 5Ω and a current of 2A, what is the voltage across the circuit? (2022)
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Solution
Using Ohm's law, V = I * R = 2A * 5Ω = 10V.
Correct Answer: A — 10V
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Q. If a circuit has a total resistance of 8Ω and a current of 4A, what is the voltage across the circuit? (2023)
A.
32V
B.
24V
C.
16V
D.
12V
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Solution
Using Ohm's law, V = IR = 4A * 8Ω = 32V.
Correct Answer: A — 32V
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Q. If a force of 15 N is applied to a 3 kg object, what is the net force acting on the object if it is already moving with a velocity of 5 m/s? (2022)
A.
15 N
B.
3 N
C.
0 N
D.
18 N
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Solution
The net force is still 15 N as it does not depend on the velocity of the object.
Correct Answer: A — 15 N
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Q. If a force of 15 N is applied to a mass of 3 kg, what is the acceleration of the mass? (2023)
A.
3 m/s²
B.
4 m/s²
C.
5 m/s²
D.
6 m/s²
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Solution
Using F = ma, a = F/m = 15 N / 3 kg = 5 m/s².
Correct Answer: B — 4 m/s²
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Q. If a force of 20 N moves an object 5 m in the direction of the force, what is the work done?
A.
100 J
B.
50 J
C.
20 J
D.
200 J
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Solution
Work = Force * Distance = 20 N * 5 m = 100 J.
Correct Answer: A — 100 J
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Q. If a person does 300 J of work in 15 seconds, what is their power output?
A.
20 W
B.
15 W
C.
25 W
D.
30 W
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Solution
Power = Work / Time = 300 J / 15 s = 20 W
Correct Answer: A — 20 W
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Q. If a person lifts a 20 kg box to a height of 2 m, what is the work done against gravity? (g = 9.8 m/s²)
A.
392 J
B.
196 J
C.
588 J
D.
784 J
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Solution
Work = m * g * h = 20 kg * 9.8 m/s² * 2 m = 392 J.
Correct Answer: B — 196 J
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Q. If a wave has a frequency of 50 Hz and a wavelength of 2 m, what is its speed? (2018)
A.
100 m/s
B.
50 m/s
C.
25 m/s
D.
200 m/s
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Solution
Wave speed = frequency × wavelength = 50 Hz × 2 m = 100 m/s.
Correct Answer: A — 100 m/s
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Q. If a wave has a frequency of 50 Hz, what is its period? (2022)
A.
0.02 s
B.
0.5 s
C.
2 s
D.
20 s
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Solution
Period (T) = 1/Frequency = 1/50 Hz = 0.02 s.
Correct Answer: A — 0.02 s
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Q. If the amplitude of a wave is doubled, how does it affect the energy of the wave? (2020)
A.
Remains the same
B.
Doubles
C.
Increases by four times
D.
Halves
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Solution
Energy of a wave is proportional to the square of the amplitude. If amplitude is doubled, energy increases by (2^2) = 4 times.
Correct Answer: C — Increases by four times
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Q. If the charge on a capacitor is doubled, what happens to the energy stored? (2019)
A.
It remains the same
B.
It doubles
C.
It quadruples
D.
It halves
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Solution
The energy stored in a capacitor is proportional to the square of the charge (U = Q^2/(2C)). Doubling the charge increases the energy by a factor of 4.
Correct Answer: C — It quadruples
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Q. If the current in an AC circuit is I(t) = 5√2 sin(100t + π/4), what is the RMS current? (2021)
A.
5 A
B.
2.5 A
C.
7.07 A
D.
3.54 A
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Solution
The RMS current is I_rms = I_peak / √2 = 5√2 / √2 = 5 A.
Correct Answer: B — 2.5 A
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Q. If the current through a resistor is tripled, what happens to the power dissipated in the resistor? (2022)
A.
Increases by 3 times
B.
Increases by 9 times
C.
Remains the same
D.
Decreases by 3 times
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Solution
Power is proportional to the square of the current (P = I²R). If I is tripled, P increases by 3² = 9 times.
Correct Answer: B — Increases by 9 times
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Q. If the electric field at a point is 1000 N/C and the charge at that point is 5 µC, what is the force experienced by the charge?
A.
0.005 N
B.
0.05 N
C.
0.5 N
D.
5 N
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Solution
F = E * q = 1000 N/C * 5 × 10^-6 C = 0.005 N.
Correct Answer: B — 0.05 N
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Q. If the frequency of a wave is halved, what happens to its wavelength? (2015)
A.
Halves
B.
Doubles
C.
Remains the same
D.
Increases by four times
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Solution
Wavelength is inversely proportional to frequency. If frequency is halved, wavelength doubles.
Correct Answer: B — Doubles
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Q. If the frequency of an AC source is doubled, how does the inductive reactance change? (2020)
A.
Doubles
B.
Halves
C.
Remains the same
D.
Quadruples
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Solution
Xl = 2πfL; if f is doubled, Xl also doubles.
Correct Answer: B — Halves
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Q. If the frequency of an AC source is doubled, what happens to the inductive reactance? (2014)
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
Inductive reactance XL = 2πfL, so if frequency f is doubled, XL halves.
Correct Answer: B — It halves
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Q. If the frequency of an AC source is doubled, what happens to the reactance of a capacitor? (2023)
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
The capacitive reactance Xc = 1/(2πfC) halves when the frequency f is doubled.
Correct Answer: B — It halves
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