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 ?
[amp_mcq option1=”1·0 A” option2=”0·5 A” option3=”0·27 A” option4=”0·7 A” correct=”option3″]
This question was previously asked in
UPSC NDA-2 – 2023
– First, calculate the resistance (R) of the heater using the initial conditions: V1 = 220 V, I1 = 0.5 A.
– R = V1 / I1 = 220 V / 0.5 A = 440 ohms.
– Now, use this resistance to find the new current (I2) when the potential difference (V2) is 120 V.
– V2 = I2 * R
– 120 V = I2 * 440 ohms
– I2 = 120 V / 440 ohms = 12 / 44 A = 3 / 11 A.
– Calculating the decimal value: 3 / 11 ≈ 0.2727 A.