In \(AC\) circuit with source voltage \(E \) = \(20\) \(sin\; 1000 \;t\) is connected to series \(L-R\) circuit whose power factor is \(\frac{1}{\sqrt 2}\) If \(E = 25\) \(sin \;2000\) \(t\), the new power factor is :
- \(\frac{2}{\sqrt5}\)
- \(\frac{1}{\sqrt5}\)
- \(\frac{1}{\sqrt3}\)
- \(\sqrt{(\frac{3}{5}})\)
The Correct Option is B
Solution and Explanation
The Correct Option is (B) : \(\frac{1}{\sqrt5}\)
Old : 
New :
R = 1000 L
\(\cos\theta=\frac{R}{Z}\)
\(=\frac{1000L}{\sqrt{(1000L)^2+(2000L)^2}}\)
\(=\frac{1}{\sqrt{1+4}}\)
\(=\frac{1}{\sqrt5}\)
Top Questions on AC Voltage
In the A.C. circuit given below, voltmeters $ V_1 $ and $ V_2 $ read 100 V each. Find the reading of the voltmeter $ V_3 $ and the ammeter A.
- COMEDK UGET - 2024
- Physics
- AC Voltage
- When an A.C. source is connected to a inductive circuit,
- COMEDK UGET - 2024
- Physics
- AC Voltage
An alternating voltage is given by \( e = 8 \sin(628.4 t) \).
Find:
(i) Peak value of e.m.f.
(ii) Frequency of e.m.f.
(iii) Instantaneous value of e.m.f. at time \( t = 10 \, {ms} \)- Alternating voltage and current in circuit is given as \(V = (100 \;sin \;ωt)\) volt
\(I = 100\;sin\bigg(ωt+\frac{π}{3}\bigg)mA\)
Find average power dissipated in circuit.- JEE Main - 2024
- Physics
- AC Voltage
- A student is provided with a variable voltage source V, a test resistor Rr = 10Ω, two identical galvanometers G1 and G2 and two additional resistors, R1 = 10MΩ and R2 = 0.001Ω. For conducting an experiment to verify ohms law, the most suitable circuit is
- JEE Main - 2023
- Physics
- AC Voltage
Questions Asked in JEE Main exam
- Let \( A = [a_{ij}] \) be a matrix of order 3 \(\times\) 3, with \(a_{ij} = (\sqrt{2})^{i+j}\). If the sum of all the elements in the third row of \( A^2 \) is \( \alpha + \beta\sqrt{2} \), where \(\alpha, \beta \in \mathbb{Z}\), then \(\alpha + \beta\) is equal to:
- JEE Main - 2025
- Matrices and Determinants
Consider the following sequence of reactions :
Molar mass of the product formed (A) is ______ g mol\(^{-1}\).- JEE Main - 2025
- Organic Chemistry
The magnitude of heat exchanged by a system for the given cyclic process ABC (as shown in the figure) is (in SI units):
- JEE Main - 2025
- Electric charges and fields
- The value of \( (\sin 70^\circ)(\cot 10^\circ \cot 70^\circ - 1) \) is:
- JEE Main - 2025
- Trigonometric Identities
- The number of 6-letter words, with or without meaning, that can be formed using the letters of the word "MATHS" such that any letter that appears in the word must appear at least twice is:
- JEE Main - 2025
- Calculus
Concepts Used:
AC Voltage
When voltage changes its direction after every half cycle is known as alternating voltage. The current flows in the circuit at that time are known as alternating current. The alternating current(AC) follows the sine function which changes its polarity concerning time. Most of the electrical devices are operating on the ac voltage.
