The current 'i' in an inductance coil varies with time 't' according to the following graph.

Which one of the following plots shows the variations of voltage in the coil?

(1)

(2)

(3)

(4)

When an ac source of e.m.f. $e=E_0\sin (100$ $t)$ is connected across a circuit, the phase difference between the e.m.f. e and the current i in the circuit is observed to be \(\frac{\pi}{4}\) as shown in the diagram. If the circuit consists only of RC or LC in series, then what is the relationship between the two elements?

In the diagram, two sinusoidal voltages of the same frequency are shown. What is the frequency and the phase relationship between the voltages?
      

1. a

2. b

3. c

4. d

Which of the following combinations should be selected for better tuning of an L-C-R circuit used for communication?

(a) $R=20\Omega , L=1.5H,C=35 \mu F$

(b) $R=25\Omega , L=2.5H,C=45 \mu F$

(c) $R=15\Omega , L=3.5H,C=30 \mu F$

(d) $R=25\Omega , L=1.5H,C=45 \mu F$

The potential differences across the resistance, capacitance and inductance are 80 V, 40 V and 100 V respectively in an L-C-R circuit. What is the power factor of this circuit?

1. 0.4             

2. 0.5

3. 0.8             

4. 1.0

A 100 $\Omega$ resistance and a capacitor of 100 $\Omega$ reactance are connected in series across a 220 V source. When the capacitor is 50% charged, the peak value of the displacement current is

(1) 2.2 A             

(2) 11A

(3) 4.4A               

(4) 11$\sqrt{2}$A

A small-signal voltage V(t)=V_o sinωt is applied across an ideal capacitor C 
(1) over a full cycle, the capacitor C does not consume any energy from the voltage source

(2) current I(t) is in phase with voltage V(t)

(3) current I(t) leads voltage V(t) by 180°

(4) current I(t) lags voltage V(t) by 90°

A transformer having efficiency of 90% is working on 200 V and 3 kW power supply. If the current in the secondary coil is 6A, the voltage across the secondary coil and the current in the primary coil respectively are
1. 300V,15A
2. 450V,15A

3. 450V,13.5A

4. 600V,15A

A coil of self-inductance L is connected in series with a bulb B and an AC source. The brightness of the bulb decreases when: