List of top Physics Questions on Alternating current asked in CBSE CLASS XII

The electric potential (V ) and electric field (⃗ E) are closely related concepts in electrostatics. The electric field is a vector quantity that represents the

Differentiate between inductive reactance, capacitive reactance and impedance of an ac circuit.
An ideal inductor and an ideal capacitor are connected in series across an ac voltage. Plot a graph showing variation of net reactance of the circuit with frequency of the applied ac voltage.

Which of the following statements is not true for electric energy in ac form compared to that in dc form?

The rms and the average value of an ac voltage \(V = V_0 \sin \omega t\) volt over a cycle respectively will be:

An alternating current is given by \( I = I_0 \cos (100\pi t) \). The least time the current takes to decrease from its maximum value to zero will be:

An AC source is connected to a resistor and an inductor in series. The voltage across the resistor and inductor are 8 V and 6 V respectively. The voltage of the source is:

An ammeter connected in series in an AC circuit reads \( 10 \, \text{A} \). The maximum value of current at any instant in the circuit is:

Differentiate between peak and rms values of alternating current. How are they related?

Draw the plots showing the variation of magnetic flux φ linked with the loop with time t and variation of induced emf E with time t. Mark the relevant values of E, φ and t on the graphs.

A voltage \( v = v_0 \sin(\omega t) \) applied to a circuit drives a current \( i = i_0 \sin(\omega t + \phi) \) in the circuit. The average power consumed in the circuit over a cycle is:

A voltage \( v = v_0 \sin(\omega t) \) applied to a circuit drives a current \( i = i_0 \sin(\omega t + \varphi) \) in the circuit. The average power consumed in the circuit over a cycle is:

(i) Draw a step-up transformer diagram. Describe its working principle. Explain 3 energy loss causes.
(ii) Does a step-up transformer violate energy conservation? Explain.
(iii) A step-up transformer (N_p=200, N_s=3000) has V_p=90V, I_s=2A. Calculate V_s and I_p.