1. In a series resonant $$LCR$$  circuit, the voltage across $$R$$ is 100 volts and $$R = 1k\Omega $$   with $$C = 2\mu F.$$   The resonant frequency $$\omega $$ is $$200 rad/s.$$   At resonance the voltage across $$L$$ is

A. $$2.5 \times {10^{ - 2}}V$$
B. $$40 V$$
C. $$250 V$$
D. $$4 \times {10^{ - 3}}V$$
Answer :   $$250 V$$
Discuss Question

2. An arc lamp requires a direct current of $$10\,A$$  at $$80\,V$$  to function. If it is connected to a $$200\,V\left( {rms} \right),50\,Hz\,AC$$     supply, the series inductor needed for it to work is close to:

A. $$0.044\,H$$
B. $$0.065\,H$$
C. $$80\,H$$
D. $$0.08\,H$$
Answer :   $$0.065\,H$$
Discuss Question

3. A step down transformer is connected to 2400 volts line and 80 amperes of current is found to flow in output load. The ratio of the turns in primary and secondary coil is $$20 : 1.$$  If transformer efficiency is $$100\% ,$$  then the current flowing in the primary coil will be

A. $$1600\,amp$$
B. $$20\,amp$$
C. $$4\,amp$$
D. $$1.5\,amp$$
Answer :   $$4\,amp$$
Discuss Question

4. A resistor and an inductor are connected to an $$ac$$  supply of $$120\,V$$  and $$50\,Hz.$$  The current in the circuit is $$3\,A.$$  If the power consumed in the circuit is $$108\,W,$$  then the resistance in the circuit is

A. $$12\,\Omega $$
B. $$40\,\Omega $$
C. $$\sqrt {\left( {52 \times 25} \right)} \,\Omega $$
D. $$360\,\Omega $$
Answer :   $$12\,\Omega $$
Discuss Question

5. A wire of resistance $$R$$ is connected in series with an inductor of reactance $${\omega L}.$$  Then quality factor of $$RL$$  circuit is

A. $$\frac{R}{{\omega L}}$$
B. $$\frac{{\omega L}}{R}$$
C. $$\frac{R}{{\sqrt {{R^2} + {\omega ^2}{L^2}} }}$$
D. $$\frac{{\omega L}}{{\sqrt {{R^2} + {\omega ^2}{L^2}} }}$$
Answer :   $$\frac{{\omega L}}{R}$$
Discuss Question

6. In an $$LCR$$  series $$a.c.$$  circuit, the voltage across each of the components, $$L, C$$  and $$R$$ is $$50V.$$  The voltage across the $$LC$$ combination will be

A. $$100 V$$
B. $$50\sqrt 2 V$$
C. $$50 V$$
D. $$0 V$$ (zero)
Answer :   $$0 V$$ (zero)
Discuss Question

7. An inductor $$20\,mH,$$  a capacitor $$50\,\mu F$$  and a resistor $$40\Omega $$  are connected in series across a source of emf $$V = 10\sin 340\,t.$$   The power loss in $$A.C.$$  circuit is :

A. $$0.51\,W$$
B. $$0.67\,W$$
C. $$0.76\,W$$
D. $$0.89\,W$$
Answer :   $$0.51\,W$$
Discuss Question

8. An inductor $$20\,mH,$$  a capacitor $$50\,\mu F$$  and a resistor $$40\,\Omega $$  are connected in series across a source of emf $$V = 10\sin 340\,t.$$    The power loss in $$AC$$ circuit is

A. $$0.67\,W$$
B. $$0.76\,W$$
C. $$0.89\,W$$
D. $$0.51\,W$$
Answer :   $$0.51\,W$$
Discuss Question

9. In an $$AC$$ circuit, the $$rms$$  value of current, $${i_{rms}}$$  is related to the peak current, $${i_0}$$ by the relation

A. $${i_{rms}} = \sqrt 2 {i_0}$$
B. $${i_{rms}} = \pi {i_0}$$
C. $${i_{rms}} = \frac{{{i_0}}}{\pi }$$
D. $${i_{rms}} = \frac{1}{{\sqrt 2 }}{i_0}$$
Answer :   $${i_{rms}} = \frac{1}{{\sqrt 2 }}{i_0}$$
Discuss Question

10. In a uniform magnetic field of induction $$B$$ a wire in the form of a semicircle of radius $$r$$ rotates about the diameter of the circle with an angular frequency $$\omega .$$ The axis of rotation is perpendicular to the field. If the total resistance of the circuit is $$R,$$ the mean power generated per period of rotation is

A. $$\frac{{{{\left( {B\pi r\omega } \right)}^2}}}{{2R}}$$
B. $$\frac{{{{\left( {B\pi {r^2}\omega } \right)}^2}}}{{8R}}$$
C. $$\frac{{B\pi {r^2}\omega }}{{2R}}$$
D. $$\frac{{{{\left( {B\pi r{\omega ^2}} \right)}^2}}}{{8R}}$$
Answer :   $$\frac{{{{\left( {B\pi {r^2}\omega } \right)}^2}}}{{8R}}$$
Discuss Question