Question
(a) In a metre bridge, the balance point is found to be at 39.5 cm from the end A, when the resistor Y is of 12.5 Ω. Determine the resistance of X. Why are the connections between resistors in a Wheatstone or Meter bridge made of thick copper strips?
(b) Determine the balance point of the bridge above if X and Y are interchanged?
(c) What happens if the galvanometer and cell are interchanged at the balance point of the bridge? Would the galvanometer show any current?
Solution
(a) Given,
Distance of jockey from end A at the balance point, l = 39.5 cm.
Standard known resistance, S = Y = 12.5 Ω
We have to determine the unknown resistance, R=X
Using the relation for balance condition we get,
Thick copper strips helps to minimise resistance of the connections and hence they are used.
(b) If, X and Y are interchanged,then, lengths are also interchanged.
Therefore, length modifies to , l =100 – 39.5 = 60.5 cm.
(c) If the galvanometer and cell are interchanged, the position of the balance point remains unchanged. Hence, the galvanometer will show no current.
Distance of jockey from end A at the balance point, l = 39.5 cm.
Standard known resistance, S = Y = 12.5 Ω
We have to determine the unknown resistance, R=X
Using the relation for balance condition we get,
Thick copper strips helps to minimise resistance of the connections and hence they are used.
(b) If, X and Y are interchanged,then, lengths are also interchanged.
Therefore, length modifies to , l =100 – 39.5 = 60.5 cm.
(c) If the galvanometer and cell are interchanged, the position of the balance point remains unchanged. Hence, the galvanometer will show no current.
