Chapter Exam

Chapter 2: Current Electricity — Online MCQ Test

Q: Ohm’s law states that, at constant temperature, the current through a conductor is proportional to its:

Answer: B. Potential difference — Ohm’s law gives V = IR for an ohmic conductor. Hence, current is directly proportional to potential difference when temperature remains constant.

Q: A metallic conductor has length L and cross-sectional area A. If its length is doubled and area is halved, its resistance becomes:

Answer: C. 4R — Resistance is given by R = ρL/A. If L becomes 2L and A becomes A/2, then R becomes 4R.

Q: Two resistors of equal resistance are connected in series across a battery. Compared to one resistor alone, the current through the circuit will be:

Answer: B. Half as much — In series, resistances add, so the total resistance doubles. Since current I = V/R, the current becomes half of that for one resistor alone.

PHYSICS · CLASS 12th · Tamil Nadu State Board

Practice Chapter 2: Current Electricity with a free chapter-wise online MCQ test for Tamil Nadu State Board CLASS 12th PHYSICS. This chapter covers: Focusing on electric current drift velocity and Ohm law this chapter examines resistance variations and Kirchhoff rules. Students master Wheatstone bridge principles meter bridge o.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 2: Current Electricity — Important Questions & Answers (FAQ)

Frequently asked questions from Tamil Nadu State Board CLASS 12th PHYSICS — Chapter 2: Current Electricity, with answers and explanations. These are sample questions; the exam has its own separate question set.

The drift velocity of electrons in a conductor is defined as:

A. Random thermal velocity of electrons
B. Average velocity acquired by electrons under an applied electric field ✓
C. Velocity of ions in the lattice
D. Velocity of light in the conductor

Answer: B. Average velocity acquired by electrons under an applied electric field
Drift velocity is the net average velocity of charge carriers when an electric field is applied. It is superimposed on their random thermal motion.

Ohm’s law states that, at constant temperature, the current through a conductor is proportional to its:

A. Resistance
B. Potential difference ✓
C. Length
D. Cross-sectional area

Answer: B. Potential difference
Ohm’s law gives V = IR for an ohmic conductor. Hence, current is directly proportional to potential difference when temperature remains constant.

A metallic conductor has length L and cross-sectional area A. If its length is doubled and area is halved, its resistance becomes:

A. R/4
B. R/2
C. 4R ✓
D. 2R

Answer: C. 4R
Resistance is given by R = ρL/A. If L becomes 2L and A becomes A/2, then R becomes 4R.

Two resistors of equal resistance are connected in series across a battery. Compared to one resistor alone, the current through the circuit will be:

A. Twice as much
B. Half as much ✓
C. Same as before
D. Four times as much

Answer: B. Half as much
In series, resistances add, so the total resistance doubles. Since current I = V/R, the current becomes half of that for one resistor alone.

Which of the following statements about a meter bridge is correct?

A. It is based on the principle of a Wheatstone bridge ✓
B. It works only when the galvanometer shows maximum deflection
C. It measures current directly
D. It cannot be used to compare resistances

Answer: A. It is based on the principle of a Wheatstone bridge
A meter bridge is a practical form of the Wheatstone bridge using a uniform wire. It is used to determine unknown resistance by the null method.