InterviewSolution
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InterviewSolution
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Experimentally prove that in parallel combination of three resistances: (a) Potential differencr across each resistor is same and (b) Total circuit current is equal to the sum of currents flowing through individual resistors. |
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Answer» Solution :PARALLEL combination of resistors: We take three resistors `R_1,R_2 and R_3` and join them in parallel between the points X and Y. COMPLETE the electric circuit as shown in Fig.12.53. (i) Plug the key and note the ammeter reading I and voltmeter reading V. so, potential difference across the parallel combination of RESISTANCES is V VOLT. (ii) Take out the plug from the key. Remove the ammeter and voltmeter from the circuit. Insert the ammeter A in series with the resistor `R_1` and voltmeter in parallel with the resistors`R_1` (i.e.,across the points L and M as shown in Fig.12.53). Plug the key and note readings of voltmeter and ammeter. Voltmeter reading is even now V but ammeter reading is `I_1`, where `I_1 lt I` (iii) Similarly measure the currents through `R_2 and R_3`. Let these be `I_2 and I_3` respectively. Also measure potential differences across points PQ and ST. Potential differences are found to be V each time. (iv) As voltmeter reading across `R_1,R_2 and R_3` is same as across the parallel combination. we conclude that in parallel combination of resistors. the total potential difference is equal to the potential difference across any one resistor.  (b) Experimentally we find that `I=I_1+I_2+I_3` It proves that in parallel arrangement of resistors the total current is equal to the sum of the currents flowing through individual resistors. 
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