Test: Alternating Current - 1 - CUET Humanities MCQ

Transformer changes low voltage alternating current to high voltage alternating current and vice-versa.

At t = 0, the inductor acts as an open circuit. So, voltage across the inductor is the same as 10-ohm resistance.
Voltage across 10-ohm resistance = 

Growth of the current in the inductor,  where 'I' is the steady state value of the current and 

L = 4/π
R = 30 ohms
Virtual voltage, E_v = 200
V_n = 50 Hz
I_v = ?
= 

I_v = 200/401.1 = 0.4986 A

Z = (R² + X_c²)^1/2
Z = (64 + 36)^1/2 = 10 ohm

The current in an LCR circuit is given by

where ω = 2πf. Thus I increases with increase in ω upto a value of ω = ω_c given by

or 
when I becomes maximum. At ω > ω_c, I decreases with increase in ω.
Hence, the correct graph is shown in option (4).

The impedance of an A.C. circuit containing resistance, inductance and capacitance is
Z = 
Z = 
Here : R = 100Ω,
L = 0.5 H
C = 10 × 10^-6 F
f = 50 Hz
Z = 
= 
= 
= 
= 189.95 ≈ 190 Ω

An induction ammeter works based on electromagnetic induction. Hence, a varying magnetic flux is required for the working of an induction ammeter. In an alternating current, the magnetic flux is continuously varying. Therefore, an induction ammeter is used for measuring the alternating current.
A permanent magnet type ammeter is used for measuring DC only.
An electrostatic voltmeter is used for measuring high voltage.
A moving iron repulsion type voltmeter is used for measuring the voltage.

E_p × I_p = 10 kW = 10 × 10³ W = 10⁴ W
I_s = 24 A
n_p/n_s = 4/1
n_p/n_s = I_s/I_p
4/1 = 24/I_p
I_p = 6 A
E_p = 10⁴/6 = 1666.7 V