For the arrangement of the potentiometer shown in the figure, the balance point is obtained at a distance 75 cm from A when the key fr is open.
The second balance point is obtained at 60 cm from A when the key k is closed. Find the internal resistance of the battery E₁.

Question

For the arrangement of the potentiometer shown in the figure, the balance point is obtained at a distance 75 cm from A when the key fr is open.

The second balance point is obtained at 60 cm from A when the key k is closed. Find the internal resistance of the battery E₁.

Infinity Learn · Accepted Answer

Let λ be resistance per unit length of wire AB. When k is opened,Iλ$$x1$$ $$=E1$$           ….(1)After$$ k is closed: Iλ$$x2$$ $$=E1$$−ir         ….$$(2)i=E1R+r$$⇒   $$r=x1x2$$−$$1$$  R  $$0.750.60$$−$$1$$ $$=$$ $$6=1.5$$  Ω  ….$$(3)

For the arrangement of the potentiometer shown in the figure, the balance point is obtained at a distance 75 cm from A when the key fr is open.
The second balance point is obtained at 60 cm from A when the key k is closed. Find the internal resistance of the battery E₁.

Remember concepts with our Masterclasses.

Ready to Test Your Skills?

free study material

For the arrangement of the potentiometer shown in the figure, the balance point is obtained at a distance 75 cm from A when the key fr is open.The second balance point is obtained at 60 cm from A when the key k is closed. Find the internal resistance of the battery E1.

Remember concepts with our Masterclasses.

Ready to Test Your Skills?

free study material

For the arrangement of the potentiometer shown in the figure, the balance point is obtained at a distance 75 cm from A when the key fr is open.
The second balance point is obtained at 60 cm from A when the key k is closed. Find the internal resistance of the battery E₁.