Question

The efficiency of a cell when connected to a resistance R is 60%. What will be the efficiency if the external resistance is increased by six times?

Answer 1

The answer is attached below

Answer 2

ANSWER:

$\bold{n^{2}=90 \%}$ is the efficiency if the external resistance is increased by six times.

EXPLANATION:

The efficiency of the cell determines the assurance as how long the cell can be used.

Efficiency of a cell can be determined by the notation n.

Efficiency of a cell (n) =  power which is used up / total amount of power.

I is the current produced by the cell.  

r is denoted as the  internal resistance of the cell.

R is denoted as the external resistance of the cell.

$\bold{n=\frac{R}{r+R}}$

$0.6=\frac{R}{r+R}$

The value of the R is calculated as  

R = 1.5r

The resistance when increased 6 times, the resultant is employed as  

$n^{2}=\frac{6 R}{6 R+r}$

$n^{2}=\frac{6 * 1.5 r}{(6 * 1.5 r)+r}$

$\bold{n^{2}=90 \%}$