NEET Current Electricity — Set 16

Question 1

In a circuit obeying Kirchhoff’s loop rule, what does a zero sum of potential changes around a closed loop imply?

Accepted Answer

Kirchhoff’s loop rule states that the algebraic sum of potential differences around a closed loop is zero, reflecting conservation of energy, as the electric potential is a conservative field.

Question 2

In a Wheatstone bridge, when the bridge is balanced, what is the potential difference across the galvanometer?

Accepted Answer

At balance, the potential at the two junctions connected to the galvanometer is equal (due to the ratio condition $ R_1 / R_2 = R_3 / R_4 $), so the potential difference across the galvanometer is zero, and no current flows through it.

Question 3

A cell of emf $ 6 \, \text{V} $ and internal resistance $ 2 \, \Omega $ is connected to an external resistor $ 4 \, \Omega $. What is the terminal voltage across the cell?

Accepted Answer

Current: $ I = \frac{\varepsilon}{R + r} = \frac{6}{4 + 2} = 1 \, \text{A} $. Terminal voltage: $ V = \varepsilon - I r = 6 - 1 \times 2 = 4 \, \text{V} $.

NEET Physics: Current Electricity — Practice Set 16

Q1. In a circuit obeying Kirchhoff’s loop rule, what does a zero sum of potential changes around a closed loop imply?

Q2. In a Wheatstone bridge, when the bridge is balanced, what is the potential difference across the galvanometer?

Q3. A cell of emf \( 6 \, \text{V} \) and internal resistance \( 2 \, \Omega \) is connected to an external resistor \( 4 \, \Omega \). What is the terminal voltage across the cell?

Q4. A cell of emf \( 8 \, \text{V} \) and internal resistance \( 2 \, \Omega \) is connected to a \( 6 \, \Omega \) resistor. What is the terminal voltage?

Q5. Why does the terminal voltage of a battery decrease when current increases?

Q6. A Wheatstone bridge has \( R_1 = 12 \, \Omega \), \( R_2 = 24 \, \Omega \), \( R_3 = 18 \, \Omega \). What is \( R_4 \) for balance?

Q7. A \( 5 \, \text{V} \) battery with \( 0.5 \, \Omega \) internal resistance is connected to a \( 4.5 \, \Omega \) resistor. What is the power dissipated in the external resistor?

Q8. A circuit has a \( 10 \, \text{V} \) battery with \( 1 \, \Omega \) internal resistance and three resistors \( 2 \, \Omega \), \( 4 \, \Omega \), \( 8 \, \Omega \) in parallel. What is the current through the \( 4 \, \Omega \) resistor?

Q9. In a circuit with parallel branches, why does the branch with the lowest resistance carry the highest current?

Q10. A \( 8 \, \Omega \) resistor carries a current of \( 2 \, \text{A} \) for \( 15 \, \text{s} \). What is the energy dissipated?