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Expert-verifiedThe current in a single-loop circuit with one resistance R is 5.0 A. When an additional resistance of 2.0 is inserted in series with R, the current drops to 4.0 A. What is R?
The value of R is.
Write for emf of the battery when the circuit has only resistance R and when R’ is inserted in the circuit using Ohm’s law. Equating them will give the value of R.
Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points.
Formulae are as follow:
Where, I is current, V is voltage, R is resistance.
Let the battery be emf V. Then, Ohm’s law gives,
When R’ is inserted in the circuit in series with R, the total resistance of the circuit becomes R+R’.
Then emf is given by,
Equating the equations 1) and 2) gives,
Hence, the value of R is .
Therefore, using Ohm’s law, the unknown resistance in the circuit can be found.
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