NEET Current Electricity — Set 5

Question 1

A $ 20 \, \text{V} $ battery with negligible internal resistance is connected to a $ 5 \, \Omega $ and $ 15 \, \Omega $ resistor in series. What is the power dissipated in the $ 15 \, \Omega $ resistor?

Accepted Answer

Total resistance: $ R = 5 + 15 = 20 \, \Omega $. Current: $ I = \frac{V}{R} = \frac{20}{20} = 1 \, \text{A} $. Power: $ P = I^2 R = 1^2 \times 15 = 15 \, \text{W} $.

Question 2

A $ 4 \, \Omega $ resistor dissipates $ 16 \, \text{W} $ of power. What is the voltage across it?

Accepted Answer

Power: $ P = \frac{V^2}{R} $. Rearrange: $ V = \sqrt{P R} $. Substitute: $ V = \sqrt{16 \times 4} = \sqrt{64} = 8 \, \text{V} $.

Question 3

A $ 20 \, \text{V} $ battery with $ 2 \, \Omega $ internal resistance delivers a current of $ 2.5 \, \text{A} $ to a resistor. What is the resistance of the resistor?

Accepted Answer

Terminal voltage: $ V = \varepsilon - I r = 20 - 2.5 \times 2 = 15 \, \text{V} $. Resistance: $ R = \frac{V}{I} = \frac{15}{2.5} = 6 \, \Omega $.

NEET Physics: Current Electricity — Practice Set 5

Q1. A \( 20 \, \text{V} \) battery with negligible internal resistance is connected to a \( 5 \, \Omega \) and \( 15 \, \Omega \) resistor in series. What is the power dissipated in the \( 15 \, \Omega \) resistor?

Q2. A \( 4 \, \Omega \) resistor dissipates \( 16 \, \text{W} \) of power. What is the voltage across it?

Q3. A \( 20 \, \text{V} \) battery with \( 2 \, \Omega \) internal resistance delivers a current of \( 2.5 \, \text{A} \) to a resistor. What is the resistance of the resistor?

Q4. A \( 8 \, \text{V} \) battery with \( 1 \, \Omega \) internal resistance is connected to a \( 7 \, \Omega \) resistor. What is the power dissipated in the internal resistance?

Q5. A copper wire carries \( 3 \, \text{A} \) with a drift speed of \( 9 \times 10^{-5} \, \text{m/s} \). If \( n = 8.5 \times 10^{28} \, \text{m}^{-3} \) and \( e = 1.6 \times 10^{-19} \, \text{C} \), what is the cross-sectional area?

Q6. A \( 24 \, \text{V} \) battery with negligible internal resistance is connected to a cubical network of 12 resistors, each \( 4 \, \Omega \). What is the total current?

Q7. A wire of length \( 5 \, \text{m} \) and resistance \( 20 \, \Omega \) is stretched to \( 10 \, \text{m} \). What is the new resistance?

Q8. A Wheatstone bridge with \( R_1 = 9 \, \Omega \), \( R_2 = 18 \, \Omega \), \( R_3 = 12 \, \Omega \), \( R_4 = 24 \, \Omega \) has a \( 20 \, \text{V} \) battery across AC and a galvanometer (\( 5 \, \Omega \)) across BD. What is the current through the galvanometer?

Q9. A \( 15 \, \text{V} \) battery with negligible internal resistance is connected to a \( 3 \, \Omega \) and \( 12 \, \Omega \) resistor in series. What is the power dissipated in the \( 12 \, \Omega \) resistor?

Q10. A \( 12 \, \Omega \) resistor dissipates \( 48 \, \text{W} \) of power. What is the current through it?