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प्रश्न
Write the principle of working of a metre bridge
उत्तर
Metre bridge follows the principle of Wheatstone bridge. Wheatstone bridge principle states that if four resistance P, Q, R and S are arranged to form a bridge as shown below with a cell ε and one way K between the points A and C and a galvanometer G between the points B and D, then on closing K, if galvanometer shows no deflection, the bridge is balanced.
Then, `P/Q=R/S`
P = resistance of the length l cm of the wire AD = lr
and Q = resistance of the length (100 - l) cm of the wire DC = (100 - l) × r.
where, r is the resistance per unit length of the wire.
संबंधित प्रश्न
In potentiometer experiment, if l1 is the balancing length for e.m.f. of cell of internal resistance r and l2 is the balancing length for its terminal potential difference when shunted with resistance R then :
A cell balances against a length of 200 cm on a potentiometer wire, when it is shunted by a resistance of 8Ω. The balancing length reduces by 40 cm, when it is shunted by a resistance of 4 Ω . Calculate the balancing length when the cell is in open circuit. Also calculate the internal resistance of the cell.
Why are the connections between the resistors in a meter bridge made of thick copper strips?
Which material is used for the meter bridge wire and why?
(a) In a metre bridge [shown in the figure], the balance point is found to be at 39.5 cm from the end A, when the resistor Y is 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?
When a resistance of 12 ohm is connected across a cell, its terminal potential difference is balanced by 120 cm length of potentiometer wire. When the resistance of 18 ohm is connected across the same cell, the balancing length is 150 cm. Find the balancing length when the cell is in open circuit. Also calculate the internal resistance of the cell.
In a meter bridge, the null point is found at a distance of l1 cm from A. If now a resistance of X is connected in parallel with S, the null point occurs at l2 cm. Obtain a formula for X in terms of l1, l2 and S.
In a meter bridge, when galvanometer and cell positions are interchanged, ______.
When a metal conductor connected to left gap of a meter bridge is heated, the balancing point ______.
In a sensitive meter bridge apparatus the bridge wire should possess ______.
