GP Electricity

If the current I through a resistor is increased by 100% (assume that temperature remains unchanged), the increase in power dissipated will be

  1. 100%
  2. 200%
  3. 300%
  4. 400%

Answer

If I is current and R is resistance then,

Power, P = I2R

Power in first case, P1 = I2R

100% increase in current means that current becomes 2I

Power in second case, P2 = (2I)2R = 4I2R

Now, increase in dissipated power = P2 – P1 = 4I2R – I2R = 3I2R

Percentage increase in dissipated power = 3P1/P1 × 100 = 300% 

The correct option is C.