Q140 / 180 · COMEDK 2024 (Evening Shift) · Physics

A transformer of $100 \%$ efficiency has 200 turns in the primary and 40000 turns in the secondary. It is connected to a $220 \mathrm{~V}$ main supply and secondary feeds to a $100 \mathrm{~K} \Omega$ resistance. The potential difference per turn is

  • A
    18 V
  • B
    11 V
  • Correct answer
    C
    1.1 V
  • D
    25 V

Solution

The transformer equation relates the primary voltage $V_p$, secondary voltage $V_s$, number of primary turns $N_p$, and number of secondary turns $N_s$ as $\dfrac{V_p}{N_p} = \dfrac{V_s}{N_s}$.

The potential difference per turn is defined as the ratio of the voltage across a coil to the number of turns in that coil.

For the primary coil, the potential difference per turn is $\dfrac{V_p}{N_p} = \dfrac{220 \text{ V}}{200 \text{ turns}} = 1.1 \text{ V/turn}$.

Since the transformer is ideal (100% efficiency), the potential difference per turn is the same for both the primary and secondary coils.

Therefore, the potential difference per turn is $1.1 \text{ V}$.

Answer: 1.1 V

Hence, the correct answer is option: 'C'.

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