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A cell of emf 1.5 V is connected with an...

A cell of emf 1.5 V is connected with an external resistance `20 Omega`. The potential difference falls to 1.0 V. The internal resistance of cell is

A

`1.5 Omega`

B

`1.0 Omega`

C

`10.0Omega`

D

`2.0Omega`

Text Solution

Verified by Experts

The correct Answer is:
C
For a cell `E=V+lr and V=lR`

`rArr (E-V)/(V)=(lr)/(IR)=(r)/(R) rArr (E-V)/(V)=(r)/(R)`
`rArr (15-10)/(10)=(r)/(20)`
`rArr r=(20xx0.5)/(10)=10 Omega`
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