Question

Numersicals
In Wheatstone's bridge
​

Answer 1

Question:

In a meter bridge the length of the wire is 100 cm. At what position will the balance point be obtained if the two resistances are in the ratio 2 : 3?

Answer:

$\Large{\underline{\underline{\bf{Option\:D:\:40\:cm}}}}$

Explanation:

$\Large{\underline{\underline{\bf{Given:}}}}$

• Length of wire = 100 cm
• Ratio of resistances = 2 : 3

$\Large{\underline{\underline{\bf{To\:Find:}}}}$

• The balance point

$\Large{\underline{\underline{\bf{Solution:}}}}$

→ Let P and Q be the two resistances. We need to find the length of the position at which balance point is obtained.

→ From the equation

  $\dfrac{P}{Q} = \dfrac{l}{100-l}$

  where l is the length

  $\dfrac{2}{3} =\dfrac{l}{100-l}$

 200 - 2l = 3l

  5l = 200

  l = 40 cm

$\boxed{\bold{Length\:=40\:cm}}$

$\Large{\underline{\underline{\bf{Notes:}}}}$

→ Meter bridge is the simplest practical application of Wheatstone bridge. It is used to measure unknown resistance.

→The factors that depend on the sensitivity of wheatstone bridge are:

• The relative position of battery and galvanometer
• The relative magnitude of resistance in the four arms of bridge.