Question

In a mixed grouping of cells, there are m identical
cells in a row and there are n such rows. Each cell
is having emf E and internal resistance r. A load
resistor R is connected to this group of cells. Then
choose the incorrect statement out of the following
(1) Current in the circuit will be maximum if
R
m
r
(2) Power transfer to load is not maximum when
current in the circuit is maximum
nE
(3) Maximum current in the circuit is
2r
n².E²R
(4) Maximum power transfer to load is
4r2​

Answer 1

Answer:

c

Explanation:

Answer 2

Concept:

Power is the amount of energy that is transferred or transformed in a certain amount of time.

Given:

There are m identical cells in a row and there are n number of rows.

Each cell has emf of E and internal resistance r.

Find:

The incorrect statement.

Solution:

The equivalent emf of the grouping of the cells is:

$E_{equ}=mE$

The equivalent resistance of the resistors in series is:

$r_{equ}=\frac{mr}{n}$

The current in the circuit is:

$I=\frac{mE}{R+\frac{mr}{n} }$

The current through a load resistor R will be maximum when R will be minimum.

Therefore, the power transfer to load is maximum when the current in the circuit is maximum.

The maximum power is:

$P=VI\\P=\frac{n^2E^2R}{4r^2}$

Therefore, the incorrect statement is (3).

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