The internal resistance of a 2.1 V cell which gives a current of 0.2 V cell which gives a current of 0.2 A through a resistance of 10Ω is

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3 years ago

Option A 1.0 Ω
Option B 0.2 Ω
Option C 0.5 Ω
Option D 0.8 Ω

Solution:

The correct option is Option.

I = E/(R+r)

$0.2 \times (10 + r) = 2.1$
$10 + r = 2.1/2 \times 10$
$r = 10.5 - 10$

$r = 0.5 Ω$