A \[750\,Hz\], \[20\,v\left( {rms} \right)\] the source is connected to the resistance of \[100\,\Omega \], an inductance of, and a capacitance of \[10\mu F\] all in series. The time in which the resistance (heat capacity \[2J\,\,per\,\deg \,\,celsius\]) will get heated by \[{10^ \circ }C\]. (assume no loss of heat to the surrounding) is close to:
A. \[245\,\,s\]
B. \[365\,\,s\]
C. \[418\,\,s\]
D. \[348\,\,s\]
Answer
303k+ views
Hint: In this question, we are going to use the formula of the impedance of the circuit and find the time in which resistance gets heated by \[{10^ \circ }C\].
Formula used:
We have been using the following formulas:
1. \[{P_{av}} = \dfrac{{V_{rms}^2}}{{{Z^2}}} \times R\]
2. \[\omega = 2\pi f\]
3. \[{P_{av}} = {V_{rms}}{I_{rms}}\cos \phi \]
4. \[Z = \sqrt {{R^2} + {X^2}} \]
5. \[t = \dfrac{{(TC) \times \Delta \theta }}{p}\]
Complete step by step solution:
w for an LCR circuit, the average power dissipated as heat is
\[{P_{av}} = \dfrac{{V_{rms}^2}}{{{Z^2}}} \times R\] where \[Z\] is the impedance of the circuit
Now the product of power and time equals the heat generated is
\[{X_L} = \omega \,L \\
\Rightarrow {X_L} = 2\pi f\,L \\
\Rightarrow {X_L} = 2\pi \times 750 \times 0.1803 \\
\Rightarrow {X_L} = 849.2\,\Omega \\ \]
And
\[{X_C} = \dfrac{1}{{\omega \,C}} \\
\Rightarrow {X_C} = \dfrac{1}{{2\pi f\,C}} \\
\Rightarrow {X_C} = \dfrac{1}{{2\pi \times 750 \times {{10}^{ - 5}}}} \\
\Rightarrow {X_C} = 21.2\,\,\,\Omega \\ \]
So,
\[X = {X_L} - {X_C} \\
\Rightarrow X = 849.2 - 21.2 \\
\Rightarrow X = 828\,\,\Omega \\ \]
And
\[Z = \sqrt {{R^2} + {X^2}} \\
\Rightarrow Z = \sqrt {{{(100)}^2} + {{(828)}^2}} \\
\Rightarrow Z = 834\,\,\Omega \\ \]
Now in the case of ac:
\[{P_{av}} = {V_{rms}}{I_{rms}}\cos \phi \\
\Rightarrow {P_{av}} = {V_{rms}} \times \dfrac{{{V_{rms}}}}{Z} \times \dfrac{R}{Z} \\
\Rightarrow {P_{av}} = {\left( {\dfrac{{{V_{rms}}}}{Z}} \right)^2} \times R \\ \]
By substituting all values, we get
\[{P_{av}} = {\left( {\dfrac{{20}}{{834}}} \right)^2} \times 100 \\
\Rightarrow {P_{av}} = 0.00575\,\,W \\ \]
Now we know that
\[U = P \times t \\
\Rightarrow U = mc\Delta \theta \\
\Rightarrow U = (TC)\Delta \theta \\ \]
So,
\[t = \dfrac{{(TC) \times \Delta \theta }}{p} \\
\Rightarrow t = \dfrac{{2 \times 10}}{{0.0575}}\,\sec \\
\therefore t = 348\,\,\sec \]
Therefore, the time in which the resistance will get heated by \[{10^ \circ }C\] is close to \[348\,\,\sec \].
Hence, option(D) is correct option
Note: The input current is equal to the output current in a series circuit, whereas the input voltage is equal to the output voltage in a parallel circuit. So, to estimate the impedance in a series circuit, we must calculate the resulting voltage, whereas in a parallel circuit, we must calculate the consequent current. The resultant voltage in a series circuit is a real number, whereas the consequent current in a parallel circuit is either a real or an imaginary number.
Formula used:
We have been using the following formulas:
1. \[{P_{av}} = \dfrac{{V_{rms}^2}}{{{Z^2}}} \times R\]
2. \[\omega = 2\pi f\]
3. \[{P_{av}} = {V_{rms}}{I_{rms}}\cos \phi \]
4. \[Z = \sqrt {{R^2} + {X^2}} \]
5. \[t = \dfrac{{(TC) \times \Delta \theta }}{p}\]
Complete step by step solution:
w for an LCR circuit, the average power dissipated as heat is
\[{P_{av}} = \dfrac{{V_{rms}^2}}{{{Z^2}}} \times R\] where \[Z\] is the impedance of the circuit
Now the product of power and time equals the heat generated is
\[{X_L} = \omega \,L \\
\Rightarrow {X_L} = 2\pi f\,L \\
\Rightarrow {X_L} = 2\pi \times 750 \times 0.1803 \\
\Rightarrow {X_L} = 849.2\,\Omega \\ \]
And
\[{X_C} = \dfrac{1}{{\omega \,C}} \\
\Rightarrow {X_C} = \dfrac{1}{{2\pi f\,C}} \\
\Rightarrow {X_C} = \dfrac{1}{{2\pi \times 750 \times {{10}^{ - 5}}}} \\
\Rightarrow {X_C} = 21.2\,\,\,\Omega \\ \]
So,
\[X = {X_L} - {X_C} \\
\Rightarrow X = 849.2 - 21.2 \\
\Rightarrow X = 828\,\,\Omega \\ \]
And
\[Z = \sqrt {{R^2} + {X^2}} \\
\Rightarrow Z = \sqrt {{{(100)}^2} + {{(828)}^2}} \\
\Rightarrow Z = 834\,\,\Omega \\ \]
Now in the case of ac:
\[{P_{av}} = {V_{rms}}{I_{rms}}\cos \phi \\
\Rightarrow {P_{av}} = {V_{rms}} \times \dfrac{{{V_{rms}}}}{Z} \times \dfrac{R}{Z} \\
\Rightarrow {P_{av}} = {\left( {\dfrac{{{V_{rms}}}}{Z}} \right)^2} \times R \\ \]
By substituting all values, we get
\[{P_{av}} = {\left( {\dfrac{{20}}{{834}}} \right)^2} \times 100 \\
\Rightarrow {P_{av}} = 0.00575\,\,W \\ \]
Now we know that
\[U = P \times t \\
\Rightarrow U = mc\Delta \theta \\
\Rightarrow U = (TC)\Delta \theta \\ \]
So,
\[t = \dfrac{{(TC) \times \Delta \theta }}{p} \\
\Rightarrow t = \dfrac{{2 \times 10}}{{0.0575}}\,\sec \\
\therefore t = 348\,\,\sec \]
Therefore, the time in which the resistance will get heated by \[{10^ \circ }C\] is close to \[348\,\,\sec \].
Hence, option(D) is correct option
Note: The input current is equal to the output current in a series circuit, whereas the input voltage is equal to the output voltage in a parallel circuit. So, to estimate the impedance in a series circuit, we must calculate the resulting voltage, whereas in a parallel circuit, we must calculate the consequent current. The resultant voltage in a series circuit is a real number, whereas the consequent current in a parallel circuit is either a real or an imaginary number.
Recently Updated Pages
If the magnetizing field on a ferromagnetic material class 12 physics JEE_Main

A point charge is placed at the corner of a cube The class 12 physics JEE_Main

What changes occur if the monochromatic light used class 12 physics JEE_Main

The unit of specific conductance is A Ohm B Ohmmetre class 12 physics JEE_Main

Which lens is used in magnifying glass A Concave lens class 12 physics JEE_Main

Sir C V Raman won the Nobel Prize in which year A 1928 class 12 physics JEE_Main

Trending doubts
Electron Gain Enthalpy and Electron Affinity Explained

What Are Current and Potential Difference in Electricity?

What Are Elastic Collisions in One Dimension?

Understanding Uniform Acceleration in Physics

Understanding Collisions: Types and Examples for Students

Isoelectronic Species: Definition, Examples & Importance

Other Pages
JEE Advanced Percentile vs Marks 2026: JEE Main Cutoff, AIR & IIT Admission Guide

Understanding the Angle of Deviation in a Prism

Dual Nature of Radiation and Matter Class 12 Physics Chapter 11 CBSE Notes - 2026-27 PDF Download (Login Required)

JEE Advanced Weightage Chapter Wise 2026 for Physics, Chemistry, and Mathematics

Understanding Average and RMS Value in Electrical Circuits

Understanding the Centre of Mass of a Semicircular Ring

