Transformer Principles – AP Physics C: E&M

Faraday's Law

$$ \frac{V_p}{V_s} = \frac{N_p}{N_s} $$

The alternating current in the primary coil creates a changing magnetic flux ($\Phi_B$) in the iron core. This changing flux induces an EMF ($V_s$) in the secondary coil.

Power Conservation

$$ P_{in} = P_{out} \implies I_p V_p = I_s V_s $$

In an ideal transformer, energy is not lost. Therefore, if voltage is stepped UP, current must be stepped DOWN to keep power balanced.

Tags

transformerFaradaymagnetic fluxAC circuits

Ideal Transformer Metrics

Sec. Voltage ($V_s$):
Sec. Current ($I_s$):

Pri. Voltage ($V_p$):
Pri. Current ($I_p$):

Power Output ($P$):

Primary Voltage ($V_p$) 120 V

Primary Turns ($N_p$) 100 Turns

Secondary Turns ($N_s$) 200 Turns

Load Resistance ($R_s$) 50 Ω

The animated dots represent alternating magnetic flux ($\Phi_B$) generated by the primary AC current. The core channels this flux to induce voltage in the secondary coil.