Section A: Objective Type Questions
The drift velocity of electrons in a metallic conductor is proportional to: (a) applied voltage (b) resistance of the conductor (c) square of the electric field strength (d) inverse of the relaxation time
Which of the following is not a unit of electrical power? (a) watt (b) joule/second (c) volt/ampere (d) kilowatt-hour
A wire of resistance R is cut into two pieces, each having a resistance of R/2. The pieces are then connected in parallel. The equivalent resistance of the combination is: (a) R/4 (b) R/2 (c) R (d) 2R
A voltmeter has a resistance of 20,000 ohms. It is used to measure the potential difference across a resistance of 1,000 ohms. The reading on the voltmeter will be: (a) 0.05 V (b) 0.5 V (c) 5 V (d) 50 V
When a current of 2 A flows through a wire for 10 s, the charge passing through any cross-section of the wire during this time is: (a) 2 C (b) 5 C (c) 10 C (d) 20 C
Section B: Short Answer Type Questions 6. Derive an expression for the equivalent resistance of three resistors connected in series.
- State and explain Kirchhoff's second law for a closed loop in an electrical circuit.
- Define the term 'electric potential' and explain its physical significance.
- Derive an expression for the energy stored in a capacitor.
- A wire of length 1 m and resistance 2 ohms is stretched to double its length. Calculate the new resistance of the wire.
Section C: Long Answer Type Questions 11. Derive an expression for the resistance of a conductor in terms of its length, cross-sectional area, and resistivity.
- Explain the working principle of a potentiometer and how it can be used to measure the emf of a cell.
- Derive an expression for the energy stored in an inductor.
- State and explain Joule's law of heating. How does it affect the efficiency of electrical appliances?
- Two resistors of resistances 3 ohms and 6 ohms are connected in parallel. A cell of emf 12 V and negligible internal resistance is connected across the combination. Calculate the current flowing through the 3 ohm resistor and the power dissipated in the 6 ohm resistor.
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