back to directory
NEET PHYSICSALTERNATING CURRENTMedium

Question

A coil of inductive reactance 31 Ω31 \, \Omega has a resistance of 8 Ω8 \, \Omega. It is placed in series with a condenser of capacitive reactance 25 Ω25 \, \Omega. The combination is connected to an a.c. source of 110110 V. The power factor of the circuit is:

A

0.56

B

0.64

C

0.8

D

0.33

Step-by-Step Solution

The power factor (cos⁡ϕ\cos \phi) of a series LCR circuit is defined as the ratio of resistance (RR) to impedance (ZZ), given by cos⁡ϕ=RZ\cos \phi = \frac{R}{Z} . First, calculate the impedance ZZ. The formula for impedance in a series LCR circuit is Z=R2+(XL−XC)2Z = \sqrt{R^2 + (X_L - X_C)^2} . Given: Resistance R=8 ΩR = 8 \, \Omega Inductive Reactance XL=31 ΩX_L = 31 \, \Omega Capacitive Reactance XC=25 ΩX_C = 25 \, \Omega Calculate the net reactance: X=XL−XC=31−25=6 ΩX = X_L - X_C = 31 - 25 = 6 \, \Omega. Calculate the impedance: Z=82+62=64+36=100=10 ΩZ = \sqrt{8^2 + 6^2} = \sqrt{64 + 36} = \sqrt{100} = 10 \, \Omega. Calculate the power factor: cos⁡ϕ=RZ=810=0.8\cos \phi = \frac{R}{Z} = \frac{8}{10} = 0.8.

Exam Context & Concepts Covered

This question aligns with the NEET PHYSICS syllabus, specifically targeting concepts from ALTERNATING CURRENT. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

PHYSICSALTERNATING CURRENTinductivereactanceresistanceplacedseries

More ALTERNATING CURRENT Questions

View all

In an alternating current circuit consisting of elements in series, the current increases on increasing the frequency of the supply. Which of the following elements are likely to constitute the circuit? (a) Only resistor (b) Resistor and an inductor (c) Resistor and a capacitor (d) Only a capacitor

A.(b), (c)
B.(a), (d)
C.(b), (d)
D.(c), (d)
MediumSolve

An AC source given by $V = V_m \sin(\omega t)$ is connected to a pure inductor $L$ in a circuit and $I_m$ is the peak value of the AC current. The instantaneous power supplied to the inductor is:

A.$\frac{V_m I_m}{2} \sin(2\omega t)$
B.$-\frac{V_m I_m}{2} \sin(2\omega t)$
C.$V_m I_m \sin^2(\omega t)$
D.$-V_m I_m \sin^2(\omega t)$
MediumSolve

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:

A.300 V, 15 A
B.450 V, 15 A
C.450 V, 13.5 A
D.600 V, 15 A
MediumSolve

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

A.0.707 A
B.1 A
C.1.414 A
D.2 A
EasySolve

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

A.25 $\Omega$
B.$10\sqrt{2} \ \Omega$
C.15 $\Omega$
D.$5\sqrt{5} \ \Omega$
MediumSolve

A 12 V, 60 W lamp is connected to the secondary of a step-down transformer, whose primary is connected to AC mains of 220 V. Assuming the transformer to be ideal, what is the current in the primary winding?

A.0.37 A
B.0.27 A
C.2.7 A
D.3.7 A
EasySolve

The variation of EMF with time for four types of generators is shown in the figures. Which amongst them can be called AC voltage?

A.(a) and (d)
B.(a), (b), (c), and (d)
C.(a) and (b)
D.only (a)
EasySolve

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. The potential difference across L, C and R is 40 V, 10 V and 40 V, respectively. The amplitude of the current flowing through the LCR series circuit is $10\sqrt{2}$ A. The impedance of the circuit will be:

A.4 $\Omega$
B.5 $\Omega$
C.$4\sqrt{2} \ \Omega$
D.$5\sqrt{2} \ \Omega$
MediumSolve

Why 32,000+ students choose TopperSquare

Everything you need to crack NEET

15,000+ Chapter MCQs

Physics, Chemistry, Biology — chapter-wise, topic-wise practice

AI Performance Analytics

Know your weak topics. Get a personalised study plan.

Full NEET Mock Tests

180 questions, timed, with detailed score analysis

PYQ Sets 2010–2024

15 years of past papers with solved explanations

Start Practising Free

No credit card · 30-second signup · Free forever plan included

This neet physics practice question is part of the TopperSquare free question bank. TopperSquare offers 15,000+ chapter-wise NEET MCQs across Physics, Chemistry, and Biology with detailed step-by-step explanations, full mock tests, NEET PYQs (2010–2024), and an AI-powered performance analytics dashboard. browse all neet practice questions → · practice physics sets →

Explore more subjects:Physics MCQs•Chemistry MCQs•Biology MCQs•Botany MCQs•Zoology MCQs•NEET Mock Tests•NEET PYQs