Question 125: AC fundamentals

Question

A common transistor radio set requires 12 V (D.C.) for its operation. The D.C. source is constructed by using a transformer and a rectifier circuit, which are operated at 220 V (A.C.) on standard domestic A.C. supply. The number of turns of secondary coil are 24, then the number of turns of primary are ___________.

Accepted Answer

In a transformer,
$${{{N_p}} \over {{N_s}}} = {{{V_p}} \over {{V_s}}}$$
where, N
p
= number of turns in primary circuit, N
s
= number of turns in secondary circuit = 24, V
p
= potential of primary circuit = 220 V and V
s
= potential of secondary circuit = 12 V
$$ \Rightarrow {{{N_p}} \over {24}} = {{220} \over {12}}$$
$$ \Rightarrow {N_p} = 440$$

AC fundamentals

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