Power in Electric Circuits Formula: P = I²R Explained with Examples

📚 Quick Study Guide

• ⚡ Electrical Power ($P$): The rate at which electrical energy is transferred in a circuit. Measured in watts (W).
• 💡 Formula: $P = I^2R$, where:
• 📈 $P$ is power (in watts)
• 전류 $I$ is current (in amperes)
• 🚧 $R$ is resistance (in ohms)
• 🧮 Understanding: Power increases with the square of the current and linearly with resistance.
• 🔍 Applications: Calculating power consumption of devices, designing circuits, and troubleshooting electrical issues.

Practice Quiz

1. What does 'P' represent in the formula $P = I^2R$?
1. (A) Potential difference
2. (B) Power
3. (C) Current
4. (D) Resistance
2. If a circuit has a current of 2A and a resistance of 5 ohms, what is the power dissipated?
1. (A) 10W
2. (B) 20W
3. (C) 30W
4. (D) 40W
3. How does increasing the current affect the power in a circuit with constant resistance?
1. (A) Power decreases linearly
2. (B) Power increases linearly
3. (C) Power decreases exponentially
4. (D) Power increases exponentially
4. A resistor in a circuit dissipates 50W of power when the current is 5A. What is the resistance of the resistor?
1. (A) 2 ohms
2. (B) 5 ohms
3. (C) 10 ohms
4. (D) 25 ohms
5. Which of the following units is used to measure electrical power?
1. (A) Amperes
2. (B) Volts
3. (C) Ohms
4. (D) Watts
6. A device has a resistance of 20 ohms and consumes 80W of power. What is the current flowing through it?
1. (A) 1A
2. (B) 2A
3. (C) 3A
4. (D) 4A
7. If both the current and resistance in a circuit are doubled, what happens to the power?
1. (A) Power doubles
2. (B) Power quadruples
3. (C) Power remains the same
4. (D) Power increases by a factor of eight