Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
Concepts Of Physics MCQ Edition [Volume 2]PhysicsAlternating Current

An electric bulb is rated to consume 55 W when operated at 110 V . It is connected in series with a choke coil across a 220 V , 50 Hz supply. Determine the inductance of the coil required for the bulb to receive its correct voltage.

Options

  1. A0.7 H
  2. B1.4 H
  3. C1.2 H
  4. D2.4 H

Correct answer

C. 1.2 H

Step-by-step solution

The rated current of the electric bulb is I = P V_R = 55 110 = 0.5 A The resistance of the bulb is R = V_R I = 110 0.5 = 220 When connected in series with a choke coil across a 220 V supply, the total voltage is V = 220 V . In a series LR circuit, the supply voltage is given by V^2 = V_R^2 + V_L^2 (220)^2 = (110)^2 + V_L^2 V_L = 220^2 - 110^2 = 110 3 V The voltage across the inductor is also given by V_L = I X_L = I (2 f L) 110 3 = 0.5 2 50 L 110 3 = 50 L L = 110 3 50 = 2.2 3 2.2 1.732 3.14 1.2 H

Practice Alternating Current on Quantrex Academy →

More from Alternating Current

Consider a circuit consisting of a capacitor of capacitance C and a coil with N turns per unit length, cross sectional area S and length d , where d^2 S . There is another coil of 2026An LCR series circuit driven with E_ rms = 90 V at frequency f_d = 30 Hz has resistance R = 80 , , an inductance with inductive reactance X_L = 20.0 , and capacitance with capacitiv 2026A series LCR circuit with R = 20 , L = 1.6 H and C = 40 F is connected to a variable frequency a.c. source. The inductive reactance at resonant frequency is _______ . 2026An a.c. source of angular frequency is connected across a resistor R and a capacitor C in series. The current is observed as I . Now the frequency of the source is changed to /4 , 2026An inductor of 10 mH, capacitor of 0.1 F and a resistor of 100 are connected in series across an a.c power supply 220 V, 70 Hz. The power factor of the given circuit is 0.5 . The d 2026The figure given below shows an LCR series circuit with two switches S₁ and S₂ . When switch S₁ is closed keeping S₂ open, the phase difference ( ) between the current and source v 2026An inductor stores 16 J of magnetic field energy and dissipates 32 W of thermal energy due to its resistance when an a.c. current of 2 A (rms) and frequency 50 Hz flows through it. 2026The electric current in the circuit is given as i=i_ o (t / T) . The r.m.s current for the period t=0 to t=T is _ _ _ _ . 2026 Full Alternating Current list All Concepts Of Physics MCQ Edition [Volume 2] PYQs