Consider an ideal transformer with primary turns

PHYSICS · Multi-part · CBSE · Physics · Alternating Current · Alternating Current

Problem

Consider an ideal transformer with

N_p

primary turns,

N_s

secondary turns and a purely resistive load

R_L

connected across the secondary. (i) Derive an expression for the equivalent resistance

R_{L}'

as it appears to the primary in terms of

N_p

N_s

and

R_L

. (ii) Hence obtain a general formula for the primary current

I_p

in terms of the primary voltage

V_p

, the turns ratio and

R_L

. (iii) A transformer with a turns ratio of 1 : 20 (primary : secondary) has

V_p = 250\,\text{V}

(rms). It supplies a load of

80\,\Omega

on the secondary. Using your result, calculate

I_p

I_s

, and comment on the equality of input and output powers.