A potentiometer P Q is set up to compare two resistances, as shown in the figure. The ammeter A in the…
A potentiometer is set up to compare two resistances, as shown in the figure. The ammeter in the circuit reads when the two-way key is open. The balance point is at a length from when the two-way key is plugged in between , while the balance point is at a length from when the key is plugged in between . The ratio of two resistances is found to be
Solution
When the key is between and
Then, emf .
When the key is between and
Emf, .
The ratio of both emf is
On simplifying the above relation, we get the ratio of resitances, .
