Ohm’s Law is a fundamental concept in electrical engineering and physics that describes the relationship between the current flowing through a conductor, the voltage across it, and its resistance. Named after the German physicist Georg Simon Ohm, the Law states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them. Mathematically, Ohm’s Law can be expressed as I = V/R, where I is the current in amperes, V is the voltage in volts, and R is the resistance in ohms. The mathematical implies that if the voltage is doubled, the current will double if the resistance remains the same. Similarly, if the resistance is doubled, the current will be halved if the voltage remains unchanged. Ohm’s Law is essential because it helps us understand and predict the behavior of electric circuits and is the basis for many practical applications in electronics and electrical engineering. For example, it can be used to calculate the power dissipated in a resistor, the efficiency of a circuit, or the voltage drop across a component. One of the critical applications of Ohm’s Law is in designing and analyzing circuits that use resistors. Resistors are components that control the flow of current in a circuit by providing a specific amount of resistance. By using Ohm’s Law, we can calculate the value of the resistor needed to achieve a desired current or voltage or to limit the current flowing through a particular component. Another critical application of Ohm’s Law is troubleshooting and diagnosing electrical circuit faults. If we know the voltage and resistance of a circuit, we can use Ohm’s Law to calculate the expected current flow. If the actual current is different from what we expect, we can use this information to identify where a fault may be occurring, such as a broken wire or a faulty component. Ohm’s Law is a fundamental electrical engineering and physics concept that describes the relationship between current, voltage, and resistance in an electric circuit. It is a powerful tool for designing courses, analyzing their behavior, and diagnosing faults. By understanding Ohm’s Law, we can better understand the behavior of electricity and use it to power our modern world. In this post Electrical Engineering Online shares Objective Electrical MCQ Questions on Earthing and Grounding.

## Ohm’s Law relates which three fundamental quantities

Ohm’s Law relates which three fundamental quantities

- Voltage, resistance, and power
- Current, resistance, and power
- Voltage, current, and resistance
- Voltage, current, and capacitance

Correct Answer: 3. Voltage, current, and resistance

**Explanation:** Ohm’s Law states that the current flowing through a conductor is directly proportional to the voltage across it and inversely proportional to the resistance.

## What is the mathematical formula for Ohm’s Law

What is the mathematical formula for Ohm’s Law?

- V = IR
- I = VR
- R = VI
- V = RI

Correct Answer: 1. V = IR

**Explanation:** V represents voltage, I represents current, and R represents resistance. According to Ohm’s Law, the voltage across a conductor equals the current flowing through it multiplied by the resistance.

## If the voltage across a resistor is 12 volts and the resistance is 4 ohms, what is the current flowing through it

If the voltage across a resistor is 12 volts and the resistance is 4 ohms, what is the current flowing through it?

- 3 A
- 16 A
- 48 A
- 0.33 A

Correct Answer: 1. 3 A

**Explanation:** Applying Ohm’s Law, I = V / R. Substituting the given values, I = 12 V / 4 Ω = 3 A.

## If the current flowing through a circuit is 2 amperes and the resistance is 10 ohms, what is the voltage across the circuit

If the current flowing through a circuit is 2 amperes and the resistance is 10 ohms, what is the voltage across the circuit?

- 20 V
- 0.2 V
- 20 V
- 8 V

Correct Answer: 3. 20 V

**Explanation:** Using Ohm’s Law, V = I × R. Substituting the given values, V = 2 A × 10 Ω = 20 V.

## What happens to the current in a circuit if the resistance is increased while the voltage remains constant

What happens to the current in a circuit if the resistance is increased while the voltage remains constant?

- The current increases
- The current decreases
- The current remains constant
- It is impossible to determine

Correct Answer: 2. The current decreases.

**Explanation:** According to Ohm’s Law, if resistance increases while voltage remains constant, the current will decrease because current is inversely proportional to resistance.

## A circuit has a resistance of 20 ohms, and the current flowing through it is 5 amperes. What is the voltage across the circuit

A circuit has a resistance of 20 ohms, and the current flowing through it is 5 amperes. What is the voltage across the circuit?

- 4 V
- 100 V
- 20 V
- 25 V

Correct Answer: 2. 100 V

## Explanation: Using Ohm’s Law, V = I × R. Substituting the given values, V = 5 A × 20 Ω = 100 V.

What is the unit of resistance

What is the unit of resistance?

- Volt
- Ampere
- Ohm
- Watt

Correct Answer: 3. Ohm

**Explanation:** Resistance is measured in ohms (Ω).

## If the voltage across a resistor is 6 volts and the current flowing through it is 3 amperes, what is the resistance

If the voltage across a resistor is 6 volts and the current flowing through it is 3 amperes, what is the resistance?

- 2 Ω
- 9 Ω
- 18 Ω
- 0.5 Ω

Correct Answer: 1. 2 Ω

**Explanation:** Applying Ohm’s Law, R = V / I. Substituting the given

values, R = 6 V / 3 A = 2 Ω.

## What will happen to the voltage across a circuit if the resistance is decreased while the current remains constant

What will happen to the voltage across a circuit if the resistance is decreased while the current remains constant?

- The voltage increases
- The voltage decreases
- The voltage remains constant
- It is impossible to determine

Correct Answer: 2. The voltage decreases

**Explanation:** According to Ohm’s Law, if resistance decreases while current remains constant, the voltage will decrease because voltage is directly proportional to resistance.

## If the current through a circuit is 0.5 amperes and the voltage across it is 12 volts, what is the resistance of the circuit

If the current through a circuit is 0.5 amperes and the voltage across it is 12 volts, what is the resistance of the circuit?

- 24 Ω
- 6 Ω
- 0.04 Ω
- 6.5 Ω

Correct Answer: 2. 6 Ω

**Explanation**: Using Ohm’s Law, R = V / I. Substituting the given values, R = 12 V / 0.5 A = 6 Ω.

## A circuit has a resistance of 100 ohms, and the voltage across it is 10 volts. What is the current flowing through the circuit

A circuit has a resistance of 100 ohms, and the voltage across it is 10 volts. What is the current flowing through the circuit?

- 0.1 A
- 100 A
- 10 A
- 1 A

Correct Answer: 1. 0.1 A

**Explanation:** Applying Ohm’s Law, I = V / R. Substituting the given values, I = 10 V / 100 Ω = 0.1 A.

## If the resistance in a circuit is 0 ohms, what can be said about the current

If the resistance in a circuit is 0 ohms, what can be said about the current?

- The current is zero
- The current is infinite
- The current is constant
- It is impossible to determine

Correct Answer: 2. The current is infinite.

**Explanation:** According to Ohm’s Law, when the resistance is zero, the current becomes infinite as I = V / R, and division by zero results in infinity.

## How is power calculated in a circuit

How is power calculated in a circuit?

- P = V / I
- P = V × I
- P = I / V
- P = R × I

Correct Answer: 2. P = V × I

**Explanation:** Power in a circuit is calculated using the formula P = V × I, where P represents power, V represents voltage, and I represents current.

## A circuit has a voltage of 24 volts and a current of 2 amperes. What is the power consumed by the circuit

A circuit has a voltage of 24 volts and a current of 2 amperes. What is the power consumed by the circuit?

- 26 W
- 12 W
- 48 W
- 48 A

Correct Answer: 3. 48 W

**Explanation:** Using the power formula, P = V × I, the power consumed by the circuit is P = 24 V × 2 A = 48 W.

## What is the unit of power

What is the unit of power?

- Volt
- Ampere
- Ohm
- Watt

Correct Answer: 4. Watt

**Explanation:** Power is measured in watts (W).

## A circuit has a power of 60 watts and a voltage of 12 volts. What is the current flowing through the circuit

A circuit has a power of 60 watts and a voltage of 12 volts. What is the current flowing through the circuit?

- 7 A
- 10 A
- 5 A
- 720 A

Correct Answer: 3. 5 A

**Explanation:** Rearranging the power formula, I = P / V, the current flowing through the circuit is I = P / V = 60 W / 12 V = 5 A.

## What happens to the power consumed by a circuit if both the voltage and current are doubled

What happens to the power consumed by a circuit if both the voltage and current are doubled?

- The power remains the same
- The power is halved
- The power is quadrupled
- The power is doubled

Correct Answer: 3. The power is quadrupled.

**Explanation:** Power is directly proportional to both voltage and current. When both voltage and current are doubled, the power is quadrupled.

## A circuit has a power of 75 watts and a resistance of 5 ohms. What is the current flowing through the course

A circuit has a power of 75 watts and a resistance of 5 ohms. What is the current flowing through the course?

- 3 A
- 375 A
- 15 A
- 25 A

Correct Answer: 1. 3 A

**Explanation:** Using the power formula, P = I^2 × R, we can rearrange it to solve for current, I = √(P / R). Substituting the given values, I = √(75 W / 5 Ω) = √15 = 3 A.

## How is resistance calculated in a circuit

How is resistance calculated in a circuit?

- R = V / I
- R = V × I
- R = I / V
- R = P / I^2

Correct Answer: 1. R = V / I

**Explanation:** Resistance is calculated using the formula R = V / I, where R represents resistance, V represents voltage, and I represents current.

## If the voltage across a circuit is 8 volts and the current flowing through it is 0.4 amperes, what is the resistance of the course

If the voltage across a circuit is 8 volts and the current flowing through it is 0.4 amperes, what is the resistance of the course

- 0.032 Ω
- 32 Ω
- 20 Ω
- 2 Ω

Correct Answer: 2. 32 Ω

**Explanation:** Applying Ohm’s Law, R = V / I. Substituting the given values, R = 8 V / 0.4 A = 32 Ω.