The correct option is (b) 2, 3 and 4 only
Explanation
The heating effect of electric current, also known as Joule’s heating, occurs when electric current flows through a conductor with resistance. The electrical energy is converted into heat energy according to the formula H = I²Rt, where I is the current, R is the resistance, and t is the time.
Statement-wise Analysis
- 1. Electric Generator: Incorrect. An electric generator works on the principle of electromagnetic induction. It converts mechanical energy into electrical energy. While some heat is produced due to resistance in the coils (energy loss), the device is not designed to utilize this heating effect; rather, it is designed to generate electricity.
- 2. Electric Geyser: Correct. An electric geyser contains a heating element made of a high-resistance material (like nichrome). When current passes through this element, significant heat is generated to warm the water, directly utilizing Joule’s heating effect.
- 3. Electric Fuse: Correct. A fuse is a safety device consisting of a wire with a low melting point. It operates on the heating effect of current. If the current exceeds a safe limit, the heat generated melts the fuse wire, breaking the circuit and preventing damage to appliances.
- 4. Electric Heater: Correct. Similar to the geyser, an electric heater uses a high-resistance coil to convert electrical energy into heat energy for warming the surroundings.
Key Takeaway: Devices like heaters, geysers, irons, and fuses are designed to exploit the conversion of electrical energy into heat (Joule's heating), whereas devices like generators and motors operate on the principles of electromagnetism.