Faraday's Law
So, when magnetic flux associated with any closed circuit changes an induced current flows, which lasts only so long as the changes lasts. And Magnitude of induced emf produced in a coil is directly proportional to rate of change of magnetic flux through coil,
Summary
So, when magnetic flux associated with any closed circuit changes an induced current flows, which lasts only so long as the changes lasts. And Magnitude of induced emf produced in a coil is directly proportional to rate of change of magnetic flux through coil,
Things to Remember
Faraday's laws
1) When magnetic flux associated with any closed circuit changes an induced current flows, which lasts only so long as the changes last.
2) Magnitude of induced emf produced in a coil is directly proportional to rate of change of magnetic flux through coil,
MCQs
No MCQs found.
Subjective Questions
Q1: What is barometer?
Type: Very_short
Difficulty: Easy
Q2: What is maximum- minimum thermometer?
Type: Very_short
Difficulty: Easy
Q3: What is hygrometer?
Type: Very_short
Difficulty: Easy
Q4: What is anemometer?
Type: Very_short
Difficulty: Easy
Q5: What is rain gauza?
Type: Very_short
Difficulty: Easy
Q6: What is meteorologist?
Type: Very_short
Difficulty: Easy
Q7: Write any one importance of weather forecasting.
Type: Very_short
Difficulty: Easy
Q8: What is weather forecasting?
Type: Very_short
Difficulty: Easy
Q9: What is humidity?
Type: Very_short
Difficulty: Easy
Q10: Which instrument is used to measure the humidity of air?
Type: Very_short
Difficulty: Easy
Q11:
Write the names of instrument used for weather forcasting.
Type: Short Difficulty: Easy
<ul>
<li>Barometer</li>
<li>Maximum- minimum thermometer</li>
<li>Hygrometer</li>
<li>Anemometer</li>
<li>Rain gauze</li>
</ul>
Q12:
Write uses of barometer and anemometer.
Type: Short Difficulty: Easy
<ul>
<li>Barometer: It is a weather instrument that is used for the measurement of atmospheric pressure.</li>
<li>Anemometer: It is a weather instrument used to measure the speed and direction of airflow.</li>
</ul>
Q13:
Write the uses of maximum- minimum thermometer, hygrometer, and rain gauze.
Type: Short Difficulty: Easy
<ul>
<li>Maximum- minimum thermometer: It is the weather instrument that is used to measure the temperature of a day in a particular time.</li>
<li>Hygrometer: It is the weather instrument that is used to measure the humidity in the air.</li>
<li>Rain gauze: It is the weather instrument that is used to measure the amount of rainfall in a particular place.</li>
</ul>
Q14:
Write any two importance of weather forecasting.
Type: Short Difficulty: Easy
<ul>
<li>Weather forecasting related to temperature and rainfall are used in agricultural sector.</li>
<li>We can plan and perform outdoor activities depending upon the weather.</li>
</ul>
Q15:
Write any three simple ways of forecasting weather.
Type: Short Difficulty: Easy
<p> </p>
<ul>
<li>If the day is partially cloudy from the morning then it might not rain in the day.</li>
<li>If the sky is suddenly covered by dark clouds then there is a high chance of rainfall.</li>
<li>The chance of rainfall increases with the sudden hot sunshine.</li>
</ul>
<p> </p>
Videos
Weather forecasting
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Faraday's Law
Faraday’s law
1) When magnetic flux associated with any closed circuit changes an induced current flows, which lasts only so long as the changes lasts.
2) Magnitude of induced emf produced in a coil is directly proportional to rate of change of magnetic flux through coil,
\begin{align*}E\alpha \frac{d\phi }{dt}\end{align*}\begin{align*}But,\oint =\int \overrightarrow{B}.d\overrightarrow{s}\end{align*}\begin{align*}E=-\frac{d}{dt}\int \overrightarrow{B}.d\overrightarrow{s}\end{align*}
Here, -ve sign shows direction of induced emf
Unit: E= weber per sec where, weber= Nm per ampere.
So, Induced Emf (E) \(\begin{align*}\overrightarrow{E}=-\frac{d\phi }{dt}\end{align*}\)
Also, on moving the conductor in magnetic field, electron around the wire experience force so, electrons have side wise motion, with velocity along the motion of conductor. Thus the electrons are pulled along length of wire, so, induced emf is also defined as the tangential force per unit charge in the conductor, taken whole length of conductor, once around complete circuit.
So,
\begin{align*}E induced=\oint \overrightarrow{E}.\overrightarrow{dl}\end{align*}\begin{align*}And,\oint =\int \overrightarrow{B}\widehat{n}.d\overrightarrow{s}\end{align*}
And, Emf induced,
\begin{align*}\oint \overrightarrow{E}.\overrightarrow{dl}=-\frac{d}{dt}\int \overrightarrow{B}.d\overrightarrow{s}\end{align*}
Using Stoke’s theorem,
\begin{align*}\oint \overrightarrow{E}.\overrightarrow{dl}=\int (\bigtriangledown \times \overrightarrow{E}).\widehat{n}ds\end{align*}\begin{align*}\int (\bigtriangledown \times \overrightarrow{E}).\widehat{n}ds=-\frac{d}{dt}\int\end{align*}
In case of stationary circuit, d/dt be taken as partial time derivation and in case of surface, two integrals are equal,
\begin{align*}\bigtriangledown \times \overrightarrow{E}=-\frac{\delta B}{\delta t}-----(i)\end{align*}
In case, B depends on position and time.
In case, B doesn’t depend on position, \(\begin{align*}\bigtriangledown \times \overrightarrow{E}=-\frac{\delta B}{\delta t}\end{align*}\)
\begin{align*}curl\overrightarrow{E}=-\frac{dB}{dt}-----(ii)\end{align*}
So (i) and (ii) represents different form of Faraday’s law.
References
Adhikari, Pitri Bhakta. A Textbook of Physics Volume-I. Kathmandu: Sukunda Pustak Bhawan, 2015.
Feynman, Richard P. The Feynman Lectures on Physics Volume 1. Noida: Dorling Kindersley (India) Pvt. Ltd., 2014.
Mathur, D S. Mechanics. New Delhi: S. Chand & Company Pvt. Ltd., 2015.
Young, Hugh D, Roger A Freedman and A Lewis Ford. University Physics. Noida: Dorling Kindersley (India) Pvt. Ltd., 2014
Lesson
Electromagnetic Induction
Subject
Physics
Grade
Bachelor of Science
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