In a meter bridge experiment null point is found at a distance of 33.7

CBSE Class 12
1

In a meter bridge experiment, null point is found at a distance of 33.7 from one end.If a 12-ohm resistor is connected in parallel with unknown resistance 10 null point is shift to 51.9. find the value of r and s

2

According to the principle of Wheatstone’s meterbridge ,
Balance condition is
image
first null point is = 33.7 cm
image
…(1)
When S is connected in parallel to R= 12 ohms
resistance across the gap is R eq
image
Thus, new balance condition is
image
…(2)
Substituting value of R/S in eq (2),
image
Thus, S= 13.68 Ω
Substituting value of S in equation (1) we get,
R = 6.91 Ω