Ohm's Law: Essential Concepts for Competitive Exam Success

Ohms Law

Q. A 10-ohm resistor has a voltage of 20 volts across it. What is the current flowing through the resistor?

A. 1 A
B. 2 A
C. 3 A
D. 4 A

Solution

Using Ohm's Law, I = V / R = 20 V / 10 Ω = 2 A.

Correct Answer: B — 2 A

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Q. A 10-ohm resistor has a voltage of 50 volts across it. What is the current flowing through the resistor?

A. 5 A
B. 10 A
C. 15 A
D. 20 A

Solution

Using Ohm's Law, I = V / R = 50 V / 10 Ω = 5 A.

Correct Answer: B — 10 A

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Q. A 10-ohm resistor is connected to a 20-volt battery. What is the power dissipated by the resistor?

A. 40 W
B. 20 W
C. 10 W
D. 2 W

Solution

Power (P) can be calculated using P = V^2 / R = 20^2 / 10 = 400 / 10 = 40 W.

Correct Answer: A — 40 W

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Q. A circuit has a voltage of 12 volts and a resistance of 4 ohms. What is the current flowing through the circuit?

A. 3 A
B. 4 A
C. 2 A
D. 1 A

Solution

Using Ohm's Law, I = V / R = 12 V / 4 Ω = 3 A.

Correct Answer: A — 3 A

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Q. A circuit has a voltage of 12V and a resistance of 4Ω. What is the current flowing through the circuit?

A. 3A
B. 4A
C. 12A
D. 48A

Solution

Using Ohm's Law, I = V/R = 12V / 4Ω = 3A.

Correct Answer: A — 3A

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Q. A circuit has a voltage of 24 volts and a current of 6 amperes. What is the resistance?

A. 4 Ω
B. 6 Ω
C. 8 Ω
D. 12 Ω

Solution

Using Ohm's Law, R = V / I = 24 V / 6 A = 4 Ω.

Correct Answer: A — 4 Ω

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Q. A resistor of 10 ohms is connected to a 20V battery. What is the current flowing through the resistor?

A. 0.5 A
B. 1 A
C. 2 A
D. 5 A

Solution

Using Ohm's Law, I = V/R = 20V / 10Ω = 2 A.

Correct Answer: C — 2 A

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Q. If a 10Ω resistor is connected to a 20V battery, what is the power dissipated by the resistor?

A. 20W
B. 40W
C. 100W
D. 200W

Solution

Power (P) can be calculated using P = V^2/R. Here, P = 20V^2 / 10Ω = 400 / 10 = 40W.

Correct Answer: B — 40W

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Q. If a 12V battery is connected across a 4 ohm resistor, what is the power dissipated in the resistor?

A. 12 W
B. 24 W
C. 36 W
D. 48 W

Solution

Power (P) can be calculated using P = V^2 / R = 12V^2 / 4Ω = 144 / 4 = 36 W.

Correct Answer: B — 24 W

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Q. If a 12V battery is connected to a 4 ohm resistor, what is the power dissipated by the resistor?

A. 12 W
B. 24 W
C. 36 W
D. 48 W

Solution

Power (P) can be calculated using P = V^2 / R = 12V^2 / 4Ω = 36 W.

Correct Answer: B — 24 W

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Q. If a 60W light bulb operates at 120V, what is the resistance of the bulb?

A. 240 ohms
B. 120 ohms
C. 60 ohms
D. 30 ohms

Solution

Power (P) = V^2 / R, so R = V^2 / P = (120V)^2 / 60W = 240 ohms.

Correct Answer: B — 120 ohms

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Q. If a circuit has a current of 0.5 A and a resistance of 20 ohms, what is the voltage?

A. 10 V
B. 5 V
C. 15 V
D. 20 V

Solution

Using Ohm's Law, V = I * R = 0.5 A * 20 Ω = 10 V.

Correct Answer: A — 10 V

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Q. If a circuit has a current of 3 A and a resistance of 4 ohms, what is the voltage across the circuit?

A. 7 V
B. 12 V
C. 15 V
D. 20 V

Solution

Using Ohm's Law, V = IR = 3 A * 4 Ω = 12 V.

Correct Answer: B — 12 V

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Q. If a circuit has a current of 5 A and a resistance of 10 Ω, what is the power consumed in the circuit?

A. 50 W
B. 25 W
C. 10 W
D. 5 W

Solution

Power (P) can be calculated using P = I^2 * R = (5 A)^2 * 10 Ω = 25 A^2 * 10 Ω = 250 W.

Correct Answer: A — 50 W

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Q. If a circuit has a current of 5 A and a resistance of 10 Ω, what is the voltage?

A. 50 V
B. 5 V
C. 10 V
D. 15 V

Solution

Using Ohm's Law, V = I * R = 5 A * 10 Ω = 50 V.

Correct Answer: A — 50 V

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Q. If a circuit has a current of 5 amperes and a resistance of 10 ohms, what is the voltage?

A. 50 volts
B. 5 volts
C. 10 volts
D. 15 volts

Solution

Using Ohm's Law, V = I * R = 5 A * 10 Ω = 50 V.

Correct Answer: A — 50 volts

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Q. If a circuit has a voltage of 24 volts and a current of 6 amperes, what is the resistance?

A. 4 Ω
B. 6 Ω
C. 8 Ω
D. 12 Ω

Solution

Using Ohm's Law, R = V / I = 24 V / 6 A = 4 Ω.

Correct Answer: C — 8 Ω

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Q. If a resistor has a resistance of 5 ohms and a current of 2 amperes flows through it, what is the voltage across the resistor?

A. 10 V
B. 5 V
C. 2.5 V
D. 1 V

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 resistor is connected to a 9V battery and the current flowing through it is 3A, what is the resistance of the resistor?

A. 1 Ω
B. 3 Ω
C. 9 Ω
D. 27 Ω

Solution

Using Ohm's Law, R = V / I = 9 V / 3 A = 3 Ω.

Correct Answer: C — 9 Ω

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Q. If the current in a circuit is 5 A and the resistance is 2 ohms, what is the power consumed in the circuit?

A. 10 W
B. 25 W
C. 5 W
D. 2.5 W

Solution

Power (P) can be calculated using P = I^2R = (5 A)^2 * 2 Ω = 25 W.

Correct Answer: B — 25 W

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Q. If the current in a circuit is doubled while the resistance remains constant, what happens to the voltage?

A. It doubles
B. It halves
C. It remains the same
D. It quadruples

Solution

According to Ohm's Law, if the current (I) is doubled and resistance (R) remains constant, the voltage (V) must also double.

Correct Answer: A — It doubles

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Q. If the resistance in a circuit is doubled while keeping the voltage constant, what happens to the current?

A. It doubles.
B. It halves.
C. It remains the same.
D. It quadruples.

Solution

According to Ohm's Law (I = V/R), if resistance (R) is doubled and voltage (V) remains constant, the current (I) will be halved.

Correct Answer: B — It halves.

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Q. If the resistance of a circuit is doubled while the voltage remains constant, what happens to the current?

A. It doubles
B. It halves
C. It remains the same
D. It quadruples

Solution

According to Ohm's Law, I = V/R. If R is doubled, the current I will be halved.

Correct Answer: B — It halves

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Q. If the voltage across a conductor is 15 volts and the current is 3 amperes, what is the resistance?

A. 5 Ω
B. 10 Ω
C. 15 Ω
D. 20 Ω

Solution

Using Ohm's Law, R = V / I = 15 V / 3 A = 5 Ω.

Correct Answer: A — 5 Ω

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Q. If the voltage across a resistor is tripled, what happens to the current through it, assuming resistance remains constant?

A. It triples.
B. It doubles.
C. It remains the same.
D. It decreases.

Solution

According to Ohm's Law (I = V/R), if voltage (V) is tripled and resistance (R) remains constant, the current (I) will also triple.

Correct Answer: A — It triples.

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Q. In a circuit, if the voltage is increased from 5V to 15V while the resistance remains constant at 5 ohms, what is the change in current?

A. Increases by 1 A
B. Increases by 2 A
C. Increases by 3 A
D. Increases by 4 A

Solution

Initial current I1 = 5V / 5Ω = 1 A; Final current I2 = 15V / 5Ω = 3 A; Change in current = I2 - I1 = 3 A - 1 A = 2 A.

Correct Answer: C — Increases by 3 A

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Q. In a circuit, if the voltage is increased while keeping the resistance constant, what happens to the current?

A. It decreases
B. It increases
C. It remains constant
D. It becomes zero

Solution

According to Ohm's Law, if voltage increases and resistance remains constant, the current will increase.

Correct Answer: B — It increases

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Q. In a circuit, if the voltage is increased while the resistance remains constant, what happens to the current?

A. It decreases
B. It increases
C. It remains the same
D. It becomes zero

Solution

According to Ohm's Law, if the voltage (V) increases and resistance (R) remains constant, the current (I) increases.

Correct Answer: B — It increases

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Q. In a parallel circuit, if one resistor fails, what happens to the total current?

A. It increases.
B. It decreases.
C. It remains the same.
D. It becomes zero.

Solution

In a parallel circuit, if one resistor fails, the total current decreases because the total resistance increases.

Correct Answer: B — It decreases.

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Q. In a series circuit, if one resistor fails (opens), what happens to the current in the circuit?

A. It increases
B. It decreases
C. It becomes zero
D. It remains the same

Solution

In a series circuit, if one resistor fails, the circuit is broken and the current becomes zero.

Correct Answer: C — It becomes zero

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Ohms Law

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