Assignment Set-1

What is a transformer? Explain its theory and discuss its main uses.

A transformer has an efficiency of $80\%$ and works at $100 \mathrm{V}$ and $4 \mathrm{kW}.$ If the secondary voltage is $240 \mathrm{V},$ calculate the primary and secondary currents.

Does the current in an A.C. circuit lag, lead or remain in phase with the voltage of frequency $f$ applied to the circuit when $f=f_r$
where $f_r$ is the resonance frequency.

Does the current in an A.C. circuit lag, lead or remain in phase with the voltage of frequency $f$ applied to the circuit when $f<f_r$
where $f_r$ is the resonance frequency.

Does the current in an A.C. circuit lag, lead or remain in phase with the voltage of frequency $f$ applied to the circuit when $f>f_r$
where $f_r$ is the resonance frequency.

Show mathematically that an ideal inductor does not consume any power in an a.c. circuit.

Alternating emf of $E=200\sin 200\pi t$ is applied to a circuit containing an inductance of $\left(\frac{1}{\pi }\right)$ henry. Then find out

Equation of instantaneous current through circuit.

Alternating emf of $E=200\sin 200\pi t$ is applied to a circuit containing an inductance of $\left(\frac{1}{\pi }\right)$ henry. Then find out
Reading of a.c. ammeter connected in the circuit.