Alternating current ATOQ

CLASS 12 PHYSICS

ATOQ

1. In an AC circuit, the direction of current changes:
   a) periodically
   b) continuously
   c) randomly
   d) never
2. The frequency of AC in India is:
   a) 50 Hz
   b) 60 Hz
   c) 100 Hz
   d) 120 Hz
3. Which device is used to measure AC voltage?
   a) Ammeter
   b) Voltmeter
   c) Ohmmeter
   d) Wattmeter
4. The peak value of AC voltage is 220V. What is its RMS value?
   a) 220V
   b) 110V
   c) 154V
   d) 311V
5. In an AC circuit, the power factor is the angle between:
   a) Voltage and resistance
   b) Voltage and current
   c) Resistance and current
   d) Resistance and reactance
6. The unit of reactance is:
   a) Ohms
   b) Farads
   c) Henrys
   d) Hertz
7. In a purely resistive AC circuit, the power factor is:
   a) 0
   b) 1
   c) -1
   d) 0.5
8. Which component of AC impedance depends on frequency?
   a) Resistance
   b) Inductance
   c) Capacitance
   d) Conductance
9. The phase difference between voltage and current in a purely capacitive circuit is:
   a) 0 degrees
   b) 90 degrees
   c) 180 degrees
   d) 270 degrees
10. A coil has an inductance of 2 H. What is its reactance at 50 Hz?
    a) 50 Ω
    b) 100 Ω
    c) 200 Ω
    d) 500 Ω
11. Which type of circuit has both resistance and capacitance?
    a) RL circuit
    b) RC circuit
    c) LC circuit
    d) RLC circuit
12. The peak current in an AC circuit is 5A. What is the RMS current?
    a) 2.5A
    b) 5A
    c) 7.07A
    d) 10A
13. Which device converts AC to DC?
    a) Transformer
    b) Capacitor
    c) Diode
    d) Inductor
14. What is the voltage across a resistor connected in series with a capacitor in an AC circuit?
    a) Equal to the supply voltage
    b) Greater than the supply voltage
    c) Less than the supply voltage
    d) Zero
15. The reactance of an inductor in an AC circuit is directly proportional to:
    a) Inductance
    b) Current
    c) Frequency
    d) Resistance
16. What happens to the impedance of a resistor in an AC circuit as the frequency increases?
    a) Increases
    b) Decreases
    c) Remains constant
    d) Depends on the resistance value
17. Which type of wave does AC voltage follow?
    a) Sine wave
    b) Square wave
    c) Triangle wave
    d) Sawtooth wave
18. In a series RLC circuit, resonance occurs when:
    a) XL = XC
    b) XL > XC
    c) XL < XC
    d) Resistance is maximum
19. The power dissipated in an AC circuit is given by:
    a) P = VI
    b) P = V^2/R
    c) P = I^2R
    d) P = V^2/X
20. Which parameter of AC voltage determines its magnitude?
    a) Amplitude
    b) Frequency
    c) Phase angle
    d) Wavelength