Alternating Current · Question 11

An ac source is connected to a capacitor C. Due to decrease in its operating frequency :

1. displacement current increases.
2. displacement current decreases.
3. capacitive reactance remains constant.
4. capacitive reactance decreases.

The net impedance of circuit (as shown in figure) will be : [figure]

1. 15
2. 5 5
3. 25
4. 10 2

The peak voltage of the ac source is equal to

1. The value of voltage supplied to the circuit
2. The rms value of the ac source
3. 2 times the rms value of the ac source
4. 1/ 2 times the rms value of the ac source

A series LCR circuit with inductance 10 H, capacitance 10 , resistance 50 is connected to an ac source of voltage, V = 200 (100t) volt. If the resonant frequency of the LCR circuit is 0 and the frequency of the ac source is , then

1. 0 = = 50 Hz
2. 0 = = 50 Hz
3. 0 = 50 Hz, = 50 Hz
4. = 100 Hz, 0 = 100 Hz

Given below are two statements In the light of the above statements, choose the most appropriate answer from the options given below

1. Statement I is incorrect but Statement II is correct
2. Both Statement I and Statement II are correct
3. Both Statement I and Statement II are incorrect
4. Statement I is correct but Statement II is incorrect

An inductor of inductance 2 mH is connected to a 220 V, 50 Hz ac source. Let the inductive reactance in the circuit is X1. If a 220 V dc source replace the ac source in the circuit, then the inductive reactance in the circuit is X2. X1 and X2 respectively are :

1. 0.628 , infinity
2. 6.28 , zero
3. 6.28 , infinity
4. 0.628 , zero

A standard filament lamp consumes 100 W when connected to 200 V ac mains supply. The peak current through the bulb will be :

1. 2 A
2. 0.707 A
3. 1 A
4. 1.414 A

An inductor of inductance L, a capacitor of capacitance C and a resistor of resistance 'R' are connected in series to an ac source of potential difference 'V' volts as shown in figure. Potential difference across L, C and R is 40 V, 10 V and 40 V, respectively. The amplitude of current flowing through LCR series circuit is 10 2 A. The impedance of the circuit is : [figure]

1. 5
2. 4 2
3. 5/ 2
4. 4

A step down transformer connected to an ac mains supply of 220 V is made to operate at 11 V, 44 W lamp. Ignoring power losses in the transformer, what is the current in the primary circuit ?

1. 4 A
2. 0.2 A
3. 0.4 A
4. 2 A

A series LCR circuit containing 5.0 H inductor, 80 F capacitor and 40 resistor is connected to 230 V variable frequency ac source. The angular frequencies of the source at which power transferred to the circuit is half the power at the resonant angular frequency are likely to be :

1. 42 rad/s and 58 rad/s
2. 25 rad/s and 75 rad/s
3. 50 rad/s and 25 rad/s
4. 46 rad/s and 54 rad/s