Chapter 2: Current Electricity — Online MCQ Test
PHYSICS · CLASS 12th · Tamil Nadu State Board
Practice Chapter 2: Current Electricity with a free chapter-wise online MCQ test.
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....
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Chapter 2: Current Electricity — Important Questions & Answers
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.
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.
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.
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.
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.
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.