NEET Current Electricity — Set 17

Question 1

In a circuit with multiple loops, what does Kirchhoff’s junction rule imply about the currents at a node?

Accepted Answer

Kirchhoff’s junction rule states that the sum of currents entering a node equals the sum leaving it, ensuring charge conservation, as charge cannot accumulate at a point in a steady-state circuit.

Question 2

What ensures that the total current entering a junction equals the total current leaving it in a complex circuit?

Accepted Answer

Kirchhoff’s junction rule, based on charge conservation, ensures that charge does not accumulate at a junction in steady state, so the sum of currents in equals the sum out.

Question 3

In a circuit with resistors in series, why does the current remain the same through each resistor?

Accepted Answer

In series, there’s only one path for current. Kirchhoff’s junction rule ensures charge conservation, so the same current flows through each resistor as no charge accumulates.

NEET Physics: Current Electricity — Practice Set 17

Q1. In a circuit with multiple loops, what does Kirchhoff’s junction rule imply about the currents at a node?

Q2. What ensures that the total current entering a junction equals the total current leaving it in a complex circuit?

Q3. In a circuit with resistors in series, why does the current remain the same through each resistor?

Q4. A \( 10 \, \text{V} \) battery with \( 2 \, \Omega \) internal resistance delivers a current of \( 2 \, \text{A} \) to a resistor. What is the resistance of the resistor?

Q5. Two cells of emf \( 3 \, \text{V} \) and \( 7 \, \text{V} \) with internal resistances \( 0.5 \, \Omega \) and \( 1.5 \, \Omega \) are connected in series with a \( 10 \, \Omega \) resistor. What is the current through the circuit?

Q6. A conductor has a resistivity of \( 7 \times 10^{-8} \, \Omega \text{m} \) and \( \alpha = 4 \times 10^{-3} \, ^\circ\text{C}^{-1} \) at \( 25^\circ \text{C} \). What is its resistivity at \( 85^\circ \text{C} \)?

Q7. A Wheatstone bridge with \( R_1 = 8 \, \Omega \), \( R_2 = 16 \, \Omega \), \( R_3 = 12 \, \Omega \), \( R_4 = 24 \, \Omega \) has a \( 10 \, \text{V} \) battery across AC and a galvanometer (\( 5 \, \Omega \)) across BD. What is the current through the galvanometer?

Q8. Why does the resistance of a conductor increase when it is stretched to double its length, assuming volume remains constant?

Q9. In a battery-powered circuit, if the external load resistance becomes very large, what happens to the current drawn from the battery?

Q10. A copper wire of cross-sectional area \( 2.5 \times 10^{-7} \, \text{m}^2 \) carries a current of \( 0.85 \, \text{A} \). If \( n = 8.5 \times 10^{28} \, \text{m}^{-3} \) and \( e = 1.6 \times 10^{-19} \, \text{C} \), what is the drift speed?