The potential difference between the two end terminals of an electric heater is 220 V and the current through it is 0.5 A. What would be the current through the heater if the potential difference across the terminals of the heater is reduced to 120 V ?

This problem is based on Ohm's Law, which states that the current passing through a conductor is directly proportional to the potential difference across its ends, provided physical conditions remain constant (V = IR).

• Step 1: Calculate the resistance (R) of the heater. Using the initial values where Potential Difference (V) = 220 V and Current (I) = 0.5 A:
  R = V / I = 220 / 0.5 = 440 Ω.
• Step 2: Calculate the new current (I') with the reduced voltage. The resistance of the heater remains the same. When the potential difference is reduced to V' = 120 V:
  I' = V' / R = 120 / 440.
  I' = 3 / 11 ≈ 0.27 A.

Thus, the current through the heater becomes 0.27 A when the potential difference is reduced to 120 V, which aligns with Option C.