How much more heat is produced if the current is doubled?
- AFour times the original amount
- BTwice the original amount
- CFive times the original amount
- DThrice the original amount
Show answer and explanation
Correct answer: (a) Four times the original amount
Explanation
By Joule's law of heating, the heat produced in a conductor is H = I²Rt. The heat varies as the square of the current.
If the current is doubled (and R and t stay the same), the heat becomes (2I)²Rt = 4I²Rt, which is four times the original amount.