Question

Difine EMF of a cell derive an expression for maximum allowed current from an EMF device​

Answer 1

Answer:

as the maximum current that can be drawn from a cell is for R =0 and it is I = E/r.

Answer 2

Electromotive Force (EMF) of a cell is defined as the maximum potential difference (V) between two electrodes of a cell.

• EMF can also be said as the total difference between the oxidation and reductio half reaction.
• EMF is a major part of electricity unit of physics as it helps in determining if the given electrochemical cell is galvanic.

Expression for maximum current from an EMF device

We know that,

Current flowing through any conductor with emf is given by

$I=\frac{E}{R+r}$ , where $E$ is the emf of the circuit, $r$ is the internal resistance, $R$ is the external resistance.

Maximum current can flow only when the internal resistance, $r$ is equivalent to $0$.

⇒$r=0$

Putting it in the above equation of current, we get

⇒$I_{max} =\frac{E}{R+0}$

⇒$I_{max} =\frac{E}{R}$

Therefore, $I_{max}$ is the maximum current allowed in any emf device.