NEET Practice Questions (MCQs) with Answers & Solutions

The context states: 'The formulae we have derived earlier for series and parallel combinations of resistors are not always sufficient to determine all the currents and potential differences in the circuit. Two rules, called Kirchhoff’s rules, are very useful for analysis of electric circuits.'

The context states: 'Junction rule: At any junction, the sum of the currents entering the junction is equal to the sum of currents leaving the junction (Fig. 3.15). For example, Fig. 3.15 shows I3 = I1 + I2, where I3 enters and I1, I2 leave.

The context states: 'If, while labelling the current I through the cell one goes from P to N, then of course $V = e + I r$ (3.60).'

The context mentions: 'Given a circuit, we start by labelling currents in each resistor by a symbol, say I, and a directed arrow to indicate that a current I flows along the resistor in the direction indicated.'

The context states: 'Gustav Robert Kirchhoff (1824 – 1887) German physicist... Mainly known for his development of spectroscopy, he also made many important contributions to mathematical physics, among them, his first and second rules for circuits.'

The text states: 'Electric circuits generally consist of a number of resistors and cells interconnected sometimes in a complicated way. The formulae we have derived earlier for series and parallel combinations of resistors are not always sufficient to determine all the currents and potential differences in the circuit. Two rules, called Kirchhoff’s rules, are very useful for analysis of electric circuits.'

The context states: 'Bending or reorienting the wire does not change the validity of Kirchhoff’s junction rule.'

The example provided states: 'It is easily verified that Kirchhoff’s second rule applied to the remaining closed loops does not provide any additional independent equation, that is, the above values of currents satisfy the second rule for every closed loop of the network.'

The context mentions: 'Given a circuit, we start by labelling currents in each resistor by a symbol, say I, and a directed arrow to indicate that a current I flows along the resistor in the direction indicated. Similarly, for each source (i.e., cell or some other source of electrical power) the positive and negative electrodes are labelled.' There is no mention of assuming all resistors are identical.

The context explains: 'This rule is also obvious, since electric potential is dependent on the location of the point. Thus starting with any point if we come back to the same point, the total change must be zero. In a closed loop, we do come back to the starting point and hence the rule.'