Electrical energy conversion to heat in kettles

Steps:

• Identify the power source: mains supply provides electrical energy to the kettle.
• Recognize the heating mechanism: electric current flows through the heating element, a resistor.
• Apply energy transfer principle: electrical work generates thermal energy via resistance (Joule heating).
• Confirm output: thermal energy heats the water inside the kettle.

Why B is correct:

• Electrical work done on the heating element converts to thermal energy by Joule's law (Q = I²Rt), where current produces heat directly.

Why the others are wrong:

• A: No chemical energy involved; kettles don't store or convert to chemicals like batteries.
• C: No mechanical work; energy comes from electricity, not motion like engines.
• D: No mechanical work input; mains supply delivers electrical, not mechanical energy.

Final answer: B