Question

A transformer has 800 turns in the primary and 40 turns in the secondary winding. The alternating e.m.f connected to the primary is 240V and the current is 0.5A

Determine

1. the secondary e.m.f
2. the power in the secondary if the transformer is 95% efficient

Answer 1

1. 
   
   Vp = 240V
   Ip = 0.5A
   ^Ns/_Np = ^Vs/_Vp
   ⁴⁰/₈₀₀ = ^Vs/₂₄₀
   Vs= ^{(40 x 240)}/₈₀₀
   =12V
2. 
   V_sI_s = 95% V_pI_p
   ⁹⁵/₁₀₀ x 240 x0.5
   =114W