current-electricity Question 41
Question: Q. 1. State Kirchhoff’s rules. Explain briefly how these rules are justified. R [Delhi I, II, III 2014]
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Solution:
Ans. Kirchhoff’s first law is known as junction rule which states that for a given junction or node in a circuit, sum of the currents entering will be equal to sum of currents leaving.
Kirchhoff’s second law is also known as loop rule which shows that around any closed loop in a circuit, sum of the potential differences across all elements will be zero
Justification : The junction rule is in accordance with the conservation of charge that serves as basis of current rule while loop rule is based on law of conservation of energy.
[CBSE Marking Scheme 2014]
[AI Q. 2. Use Kirchhoff’s rules to obtain conditions for the balance condition in a Wheatstone bridge.
A [Delhi I, II, III 2015]
Ans. Applying Kirchhoff’s loop rule to closed loop ADBA
For loop
from equation (i)
From equation (ii)
