Current Electricity is a Class 12 Physics chapter that carries about 6.9% of the Physics questions in NEET. Practise it with 57 questions covering 6 topics, each with an explanation.
Sample questions on Current Electricity with answers
8 questions from the practice bank, spread across the chapter's topics. The full set is in the app.
Question 1: EMF, Internal Resistance and Cell Combinations
Four identical cells of emf 1.5 V and internal resistance 0.5 Ω each are connected in parallel. The emf and internal resistance of the combination are:
- A 6 V and 2 Ω
- B 1.5 V and 2 Ω
- C 1.5 V and 0.125 Ω
- D 6 V and 0.125 Ω
Answer: C. 1.5 V and 0.125 Ω
Why: In parallel the emf stays the same, and the internal resistance falls to r/n.
Question 2: Kirchhoff's Laws
A cell of emf E and internal resistance r drives a current I through an external resistance R. Kirchhoff's loop rule gives:
- A E − Ir + IR = 0
- B E = Ir − IR
- C E + Ir + IR = 0
- D E − Ir − IR = 0
Answer: D. E − Ir − IR = 0
Why: The rise in potential across the cell is used up in the internal and external resistances.
Question 3: Ohm's Law and Resistance
The SI unit of electrical resistance is:
- A Ohm
- B Siemens
- C Farad
- D Henry
Answer: A. Ohm
Why: Resistance is measured in ohms (Ω), defined as volts per ampere. Siemens is the unit of conductance (1/resistance); farad measures capacitance; henry measures inductance.
Question 4: Potentiometer
The sensitivity of a potentiometer can be increased by:
- A using a thicker wire
- B increasing the current through the wire
- C increasing the length of the potentiometer wire
- D decreasing the length of the wire
Answer: C. increasing the length of the potentiometer wire
Why: A longer wire has a smaller potential gradient, so a small difference in emf corresponds to a larger shift of the balance point.
Question 5: Series and Parallel Combination of Resistors
Two resistors of 4 Ω each are connected in parallel. Their equivalent resistance is:
- A 2 Ω
- B 4 Ω
- C 8 Ω
- D 1 Ω
Answer: A. 2 Ω
Why: 1/R = 1/4 + 1/4 = 1/2, so R = 2 Ω.
Question 6: Wheatstone Bridge and Meter Bridge
In a meter bridge, a known resistance of 6 Ω is in the right gap. The balance point is 40 cm from the left end. The unknown resistance in the left gap is:
- A 9 Ω
- B 6 Ω
- C 4 Ω
- D 2.4 Ω
Answer: C. 4 Ω
Why: X/6 = l/(100 − l) = 40/60, so X = 4 Ω.
Question 7: EMF, Internal Resistance and Cell Combinations
A cell of emf 2 V and internal resistance 0.1 Ω is short-circuited with a wire of negligible resistance. The current is:
- A 20 A
- B 2 A
- C 200 A
- D 0.2 A
Answer: A. 20 A
Why: I = E/r = 2/0.1 = 20 A.
Question 8: Kirchhoff's Laws
A 12 V battery of negligible internal resistance is connected in series with 2 Ω and 4 Ω resistors. The current in the circuit is:
- A 6 A
- B 2 A
- C 1 A
- D 3 A
Answer: B. 2 A
Why: By the loop rule, 12 = I(2 + 4), so I = 2 A.