Current Electricity Quiz - CBSE Class 12 Physics
Free practice quiz: Current Electricity (CBSE Class 12 Physics). 21 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
Play all 21 questions freeSample questions
What is the SI unit of electric current?
- Volt
- Ampere
- Ohm
- Coulomb
Show answer
Answer: B. Ampere
The SI unit of electric current is the ampere (A), which measures the rate of flow of electric charge.
How does the resistance of a conductor change with temperature?
- It always increases
- It always decreases
- It remains constant
- It depends on the material
Show answer
Answer: D. It depends on the material
The resistance of a conductor changes with temperature; for most metals it increases, but for some materials like semiconductors, it can decrease.
Explain the principle behind a potentiometer.
- Ohm's law
- Kirchhoff's laws
- Conservation of charge
- Comparison of potential drops
Show answer
Answer: D. Comparison of potential drops
A potentiometer compares the potential drop across an unknown resistance with that across a known resistance to determine the unknown resistance.
Derive an expression for the equivalent resistance of two resistors connected in series.
- R = R1 + R2
- R = R1R2/(R1 + R2)
- R = R1 - R2
- R = R1/R2
Show answer
Answer: A. R = R1 + R2
In a series connection, the same current flows through both resistors. The total voltage is the sum of the individual voltage drops across each resistor, leading to R = R1 + R2.
Explain the concept of electric mobility.
- The ratio of drift velocity to the electric field
- The ratio of electric field to drift velocity
- The product of drift velocity and electric field
- The ratio of current to electric field
Show answer
Answer: A. The ratio of drift velocity to the electric field
Electric mobility is a measure of how easily a charge carrier moves through a material under the influence of an electric field.