Question

please guys answer it fast and also check my last questions ​

Answer 1

Working principle:

• Potential difference across length of potentiometer wire is proportional to the length of the wire.
• €=kL where € is the emf and k is the potential gradient.
• In the figure points 1, 2, 3 form a two key way.
• Consider first position of key where 1 and 3 are connected so the galvanometer is connected to € 1 .
• Jockey is moved at a point till L1 distance from A1 to point N1 .
• Then € = kL1
• Similarly, if another emf €2 is balanced against l2 (AN2)
• €2 = kL2

Dividing both equations we finally get:

$\frac{ €_{1} }{€_{2}} = \frac{l_{1}}{l_{2}}$