Write down the formula for the heat produced when a current I is passed through a resistor R for time t.

Explain why, filament type electric bulbs are not power efficient.

Why does the connecting cord of an electric heater not glow hot while the heating element does ?

An electric iron of resistance 20 ohms draws a current of 5 amperes. Calculate the heat produced in 30 seconds.

State three factors on which the heat produced by an electric current depends. How does it depend on these factors?