Question:
A transformer has 50 turns in the primary and 100 in the secondary. What will the voltage across the secondary be if the primary is connected to a 220 V DC supply?
A transformer has 50 turns in the primary and 100 in the secondary. What will the voltage across the secondary be if the primary is connected to a 220 V DC supply?
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Transformers need changing flux; steady DC gives no induced EMF in the secondary.
Updated On: Jul 2, 2026
- 440
- 220
- 110
- Zero Volts
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The Correct Option is D
Solution and Explanation
Step 1: A transformer works only on the principle of electromagnetic induction, which requires a continuously changing magnetic flux through the core.
Step 2: A steady DC supply produces a constant current in the primary and therefore a constant flux \(\Phi\). Since \(\dfrac{d\Phi}{dt}=0\), no EMF is induced in the secondary.
Step 3: By Faraday's law the secondary voltage is
\[V_s=-N_s\frac{d\Phi}{dt}=0.\]
Step 4: The turns ratio (100/50) is irrelevant here because there is no time-varying flux. Hence the secondary voltage is zero volts, option (D).
\[\boxed{V_s=0\,\text{V}}\]
Step 2: A steady DC supply produces a constant current in the primary and therefore a constant flux \(\Phi\). Since \(\dfrac{d\Phi}{dt}=0\), no EMF is induced in the secondary.
Step 3: By Faraday's law the secondary voltage is
\[V_s=-N_s\frac{d\Phi}{dt}=0.\]
Step 4: The turns ratio (100/50) is irrelevant here because there is no time-varying flux. Hence the secondary voltage is zero volts, option (D).
\[\boxed{V_s=0\,\text{V}}\]
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