Question

1.
7
A cell of internal resistance r connected across an external resistance R
can supply maximum current when
(A) R=r
(B) R>r
R=I
(D)
R=0
dator+boot​

Answer 1

Answer:

Option A; R = r

Explanation:

Maximum current in a circuit flows when the internal resistance is equal to the resistance of the load.

Mathematically, it can be proved as;

Series combination of cells, Current I= nE / (nr+R′)........a

If we consider parallel combination of cells,

I′=E / {(r/n)+R}...................b

When I = I’

Computing above two equations a and b;

We get r = R

Answer 2

Complete question:

A cell of internal resistance r is connected to an external resistance R. The current will be maximum in R, if

A. R = r

B. R < r

C. R > r

D. R = r/2

Answer:

The current will be maximum in R, if A. R = r

Explanation:

The current in the series combination is given by the formula:

I = nE/(nr + R')

The current in the parallel combination is given by the formula:

I' = E/(r/n + R)

If I = I', then

nE/(nr + R') = E/(r/n + R)

n(r/n + R) = (nr + R')

r + nR = nr + R'

On computing, we get,

∴ r = R