Question

Ans.
4. In metre bridge X and 2X resistance are connected in left and right gap respectively. Null point is obtained at ..
(a) 33.3cm from right end (b) 33.3cm from left end (C) 66.6cm from left end (d) 40cm from left end
Ans. :​

Answer 1

Given:

In meter bridge X and 2X resistance are connected in left and right gap respectively.

To Choose?

Null point is obtained at

(a) 33.3cm from right end

(b) 33.3cm from left end

(C) 66.6cm from left end

(d) 40cm from left end

Solution:

given that - in a meter-bridge X and 2X resistance are connected in left and right gap respectively.

since, we know that- ratio of resistance is directly proportional to the ratio of the length at which null point obtained.

therefore,

$\dfrac{X}{2X}= \dfrac{l}{100-l}\\\\\dfrac{1}{2}=\dfrac{l}{100-l}\\\\100-l=2l\\\\3l=100\\\\l=33.33$

Hence, null point obtained at 33.3cm from the left end of the meter-bridge.

Thus, option (b) is correct.