Question

In an electric circuit applied ac emf is \[e = 20sin300t\] volt and the current is \[I = {\text{ }}4sin300t\] ampere. The reactance of the circuit is-
\[\left( {\text{A}} \right){\text{ }}5\] ohm
\[\left( {\text{B}} \right){\text{ }}80\] ohm
\[\left( {\text{C}} \right){\text{ }}1.8{\text{ }}k\Omega \]
$\left( {\text{D}} \right){\text{ }}$ Zero

Answer 1

Hint: Electromotive Force is defined as the energy per unit charge causing the charge to move through the circuit. EMF is not exactly a force; instead it is the measurement of energy or work done per charge which causes the charge to move around in a circuit.
Ohm’s law: This law states that the voltage drops or the electromotive force across the circuit are directly proportional to the current flow in the circuit.

Complete step by step answer:
${\text{emf = IR}}$,
Here emf= electromotive force, \[I = \] current across the circuit, \[R = \] resistance of the resistor
Complete step-by-step solution:
It is given in the question that,
Emf, \[e = 20sin300t\]
Current, \[I = {\text{ }}4sin300t\] ampere
Therefore, we can calculate the reactance of the circuit, ${\text{R = }}\dfrac{{{\text{emf}}}}{{\text{i}}}$
Putting the given values and we get,
$ \Rightarrow \dfrac{{20}}{4}$
Let us divide the term we get,
$ \Rightarrow 5\Omega $
Hence the correct option is \[\left( {\text{A}} \right)\]

Note: A circuit is always a closed path only then the current flows through it.
A circuit always contains at least an energy source that acts as a source of electrons and it is the reason for the generation of electric current. The electric elements contain an uncontrolled and controlled source of energy, resistors, capacitors, inductors, etc. in the circuit.
In an electric circuit, the electrons move from the negative terminal to the positive terminal in the circuit. The Direction of the flow of current is from positive to negative terminal in the circuit. The Flow of current leads to potential drop across the various elements in the circuit.