A 10 Ω, 20 mH coil carrying constant current is connected to a battery of 20 V through a switch. Now after switch is opened current becomes zero in 100 μs. The average e.m.f. induced in the coil is ____V
Correct Answer: 400
Solution and Explanation
Initial flux through inductor = LI
\(⇒\) \(\phi_i = 20 \times 10^{-3} \times \left(\frac{20}{10}\right) = 4 \times 10^{-2}\) weber
Final flux \(= 0\)
\(⇒\) average emf \(=\) \(\frac{|\phi_i - \phi_f|}{100 }\, \mu \text{s}\)
\(=\)\(\frac{4 \times 10^{-2}}{10^{-4}}=400\ V\)
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Concepts Used:
Electric Current
Defining Electric Current
It is the rate of flow of electrons in a conductor. SI Unit - Ampere (A).
Electrons are negatively charged particles hence when they move a number of charges moves.
Note:- The ability of a particular substance to conduct electricity depends on the number of electrons that are able to move . Some of the materials allow current to flow better than others.
What is an Electromotive Force?
If a force acts on electrons to make them move in a particular direction, then up to some extent random motion of the electrons will be eliminated. An overall movement in one direction. The force which acts on the electrons to move them in a certain direction is known as electromotive force and its quantity is known as voltage and is measured in V.