JEE Main Alternating Current Practice Questions With Solutions

An AC voltage $V=20\sin 200\pi t$V = 20 sin ⁡ 200 \pi t is applied to a series LCR circuit which drives a current $I=10\sin (200\pi t+\frac{\pi }{3})$I = 10 sin ⁡ \left(\right. 200 \pi t + \frac{\pi}{3} \left.\right). The average power dissipated is:

An alternating voltage $V(t)=220\sin 100\pi t$V \left(\right. t \left.\right) = 220 sin ⁡ 100 \pi t volt is applied to a purely resistive load of $50\mathrm{\Omega }$50 \Omega. The time taken for the current to rise from half of the peak value to the peak value is:

Primary coil of a transformer is connected to $220\mathrm{V}$220 \textrm{ } V ac. Primary and secondary turns of the transforms are 100 and 10 respectively. Secondary coil of transformer is connected to two series resistances shown in figure. The output voltage $\left(V_0\right)$\left(\right. V_{0} \left.\right) is :

A series L.R circuit connected with an ac source $E=(25\sin 1000t)V$E = \left(\right. 25 sin ⁡ 1000 t \left.\right) V has a power factor of $\frac{1}{\sqrt{2}}$\frac{1}{\sqrt{2}}. If the source of emf is changed to $\mathrm{E}=(20\sin 2000\mathrm{t})\mathrm{V}$E = \left(\right. 20 sin ⁡ 2000 t \left.\right) V, the new power factor of the circuit will be :

In an a.c. circuit, voltage and current are given by:

$V=100\sin (100t)V$V = 100 sin ⁡ \left(\right. 100 t \left.\right) V and$I=100\sin (100t+\frac{\pi }{3})\mathrm{mA}$I = 100 sin ⁡ \left(\right. 100 t + \frac{\pi}{3} \left.\right) mA respectively.

The average power dissipated in one cycle is:

A capacitor of capacitance $100\mu \mathrm{F}$100 \mu F is charged to a potential of $12\mathrm{V}$12 \textrm{ } V and connected to a $6.4\mathrm{mH}$6.4 \textrm{ } mH inductor to produce oscillations. The maximum current in the circuit would be :

Primary side of a transformer is connected to $230\mathrm{V},50\mathrm{Hz}$230 \textrm{ } V , 50 \textrm{ } Hz supply. Turns ratio of primary to secondary winding is $10:1$10 : 1. Load resistance connected to secondary side is $46\mathrm{\Omega }$46 \Omega. The power consumed in it is :

Given below are two statements:

Statement I : An AC circuit undergoes electrical resonance if it contains either a capacitor or an inductor.

Statement II : An AC circuit containing a pure capacitor or a pure inductor consumes high power due to its non-zero power factor.

In the light of above statements, choose the correct answer form the options given below:

Given below are two statements:

Statement I : When the frequency of an a.c source in a series LCR circuit increases, the current in the circuit first increases, attains a maximum value and then decreases.

Statement II : In a series LCR circuit, the value of power factor at resonance is one.

In the light of given statements, choose the most appropriate answer from the options given below.

As per the given graph, choose the correct representation for curve $\mathrm{A}$A and curve B.

Where ${\mathrm{X}}_{\mathrm{C}}=$X_{C} = reactance of pure capacitive circuit connected with A.C. source

${\mathrm{X}}_{\mathrm{L}}=$X_{L} = reactance of pure inductive circuit connected with $\mathrm{A}.\mathrm{C}$A . C. source

R = impedance of pure resistive circuit connected with A.C. source.

$\mathrm{Z}=$Z = Impedance of the LCR series circuit $\}$\left.\right}