To verify the laws of combination (series & parallel) of resistances using meter bridge (slide Wire Bridge)
A meter bridge, laclanche cell, a galvanometer, a resistance box, a jockey, two resistances wires, set square, sand paper and connecting wires.
| Resistant Coil | Obs. No. | Resistance from resistance box,R (ohm) | Length BC = (100-ι) cm | Resistance r = 100-ι/ι.R | Mean Resistant (ohm) | |
| r1only | 1/2/3 | 0.5/1.0/1.5 | 35/43/50 | 65/57/50 | 0.92/1.32/1.5 | 1.24 | r2only | 1/2/3 | 0.5/1.0/1.5 | 30/38/46 | 70/62/54 | 0.16/1.63/1.76 | 1.51 |
| r2 & r 2 in series | 1/2/3 | 1.3/2.2/3.5 | 34/45/54 | 66/55/46 | 2.52/2.68/2.97 | 1.72 |
| r2 & r 2 in parllel | 1/2/3 | 2/3/4 | 75/82/86 | 25/18/14 | 0.67/0.66/0.65 | 0.66 |
In Series: Experimental value of R S= 2.72Ω
Theoretical value of RS=r1+ r 2= 2.75Ω
In Series: Experimental value of R S= 2.72Ω
In parallel: Experimental value of R P=0.66Ω
Theoretical value of RP=r1r2 /r1+ r2= 0.68Ω
Result:Within limits of experimental error, experimental & theoretical values of R Sare same. Hence the law of resistance in series i.e. R s= r 1+ r 2 is verified. (1) Within limits of experimental error, experimental & theoretical values of R p are same. Hence law of resistances in parallel i.e. Rs= r1r2/r1+r2 is verified.
Precautions:
Sources of Error:
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