Question

An electric wire is connected across a cell of e.m.f \[E\]. The current $I$ is measured by an ammeter of resistance \[R\] . According to ohm's law
A. $E = {I^2}R$
B. $E = IR$
C. $E = \dfrac{R}{I}$
D. $E = \dfrac{I}{R}$

Answer 1

Hint: Ohm's Law states that the current flowing through a conductor is directly proportional to the potential difference across it when the temperature is constant. Similar to this, the electromotive force (e.m.f.) is the power a cell or battery produces for each unit of charge that passes through it.

Formula used:
According to the Ohm’s law,
$V = IR$
Where, $V$ is the potential difference, $I$ is the current and $R$ is the resistance of the conductor.

Complete step by step solution:
According to Ohm's law, electric current is directly proportional to voltage across two points and inversely proportional to resistance. Ohm's law, which gives the relationship between the voltage and the current by taking into account the resistance value, is crucial to understanding how electric circuits work.

Therefore, from Ohm’s law we know that, $V \propto I$ which implies that $V = RI$ taking $R$ as the proportionality constant and is known as resistance. When there is no current flowing through the cell, the potential difference across its terminals is what creates electromotive force. When no current is flowing, electromotive force (EMF) equals the terminal potential difference.

Despite the fact that both EMF and terminal potential difference (V) are expressed in volts, they cannot be considered as the same physical quantity. EMF is the quantity of energy \[\left( E \right)\] that the battery supplies to each coulomb of charge \[\left( Q \right)\] that passes through. In the given question the potential difference applied is $E$ that is, the given electromotive force. Therefore, $E = RI$.

Hence, option B is the correct answer.

Note: Since Ohm’s law is dependent on the physical characteristics of the conductor, such as temperature, pressure, and so forth, Ohm's Law is not a universal law like Newton's Law of Gravitation. Even appliances do not always adhere to Ohm's law.