Concept:Transformers step down high AC mains voltage (e.g., 220 V) to the lower voltages required by semiconductor circuits, while providing galvanic isolation for safety.
Formula:$$\frac{V_s}{V_p} = \frac{N_s}{N_p} < 1 \quad (\text{Step-Down})$$
Solution:- Directly connecting \( 220\text{ V} \) mains to standard diodes would exceed their reverse breakdown voltage and destroy low-voltage DC electronics.
- A step-down transformer reduces the peak voltage to safe levels (e.g., 12 V) and provides electrical isolation from the AC mains.
Why other options are incorrect:- Option A: Transformers operate via mutual magnetic induction and only pass AC; they cannot rectify AC to DC.
- Option C: Passive transformers do not alter the input signal frequency.
- Option D: Diodes are still required to rectify the stepped-down AC voltage.
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