CBSE Class 12 · 2020 · Alternating CurrentVery Short Answer

An a.c. voltage is applied across an ideal inductor. The current in it

(a)(i) You are given three circuit elements X, Y and Z. They are connected one by one across a given a.c. source. It is found that V and I are in phase for element X, V leads I by $\frac{\pi }{2}$ for element Y, while I leads V by $\frac{\pi }{2}$ for element Z. Identify the elemen …

(b)(i) Describe the construction and working of a transformer and hence obtain the relation for $\frac{V_s}{V_p}$ in terms of the number of turns of the primary and secondary. (ii) Discuss four main causes of energy loss in a real transformer.

A series RC circuit with $R=200\Omega$ and $C=\left(\frac{50}{\pi }\right)\mu \text{F}$ is connected across an a.c. source of peak voltage ${\epsilon }_0=100$ V and frequency $\nu =50$ Hz. Calculate
(a) the impedance of the circuit ($Z$),
(b) the phase angle ($\varphi$), and
(c) the …

A resistance R and a capacitor C are connected in series to a source $V=V_0\sin \omega t$. Find: (a) the peak value of the voltage across (i) the resistance and (ii) the capacitor; (b) the phase difference between the applied voltage and the current — which of them is ahead?

(a) With the help of a labelled diagram, explain the working of a step-up transformer. Give reasons to explain the following: (i) the core of the transformer is laminated, (ii) thick copper wire is used in the windings. (b) A conducting rod PQ of length 20 cm and resistance …