Advertisements
Advertisements
प्रश्न
The figure shows experimental set up of a meter bridge. When the two unknown resistances X and Y are inserted, the null point D is obtained 40 cm from the end A. When a resistance of 10 Ω is connected in series with X, the null point shifts by 10 cm. Find the position of the null point when the 10 Ω resistance is instead connected in series with resistance ‘Y’. Determine the values of the resistances X and Y.
Advertisements
उत्तर
For a metre bridge:
`X/Y = l_1/(100 - l_1)`… (1)
Where, it is given that l1 = 40 cm
`X/Y = 40/(100 -40) = 2/3`… (2)
When 10 Ω resistance is added in series to X, null point shifts by 10 cm.
`(X+10)/Y = (40+10)/(100 - (40 +10))`
`X +10 = 50/50`
`(X+10)/Y = 1 or X+10 = Y ..... (3)`
Substituting the value of X from equation (2), we obtain
`2/3y+10 = Y`
`10 = Y -2/3 Y`
or
`Y/3 =10`
`Y =30 Omega`
Substituting the value of Y in equation (3), we obtain
X + 10 = 30
X = 20 Ω
Position of the null point when 10 Ω resistance is put in series with Y,
`20/(30+10) = l_i/(100 - l_i)`
`2000 - 20l_1 = 40l_1`
`60l_1 = 2000`
`l_1 = 2000/60`
`l_1 = 33.3 cm`
APPEARS IN
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 :
The instrument which can measure terminal potential difference as well as electromotive force (e.m. f.) is ______
- Wheatstone’s meter bridge
- Voltmeter
- Potentiometer
- Galvanometer
State any ‘two’ possible sources of errors in meter-bridge experiment. How can they be minimised?
Which material is used for the meter bridge wire and why?
A resistance of R Ω draws current from a potentiometer as shown in the figure. The potentiometer has a total resistance Ro Ω. A voltage V is supplied to the potentiometer. Derive an expression for the voltage across R when the sliding contact is in the middle of the potentiometer.
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.
Write the principle of working of a metre bridge
In a metre bridge, the balance point is found at a distance l1 with resistances R and S as shown in the figure.An unknown resistance X is now connected in parallel to the resistance S and the balance point is found at a distance l2. 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 ______.
