Question 1

State Ohm's Law and explain the physical significance of electrical resistance. Also, mention the factors on which the resistance of a conductor depends.

Accepted Answer

Ohm's Law states that at a constant physical temperature and mechanical state, the electric current ($I$) flowing through a conductor is directly proportional to the potential difference ($V$) applied across its ends. Mathematically, it is expressed as $V = IR$, where $R$ is a constant of proportion

Question 2

State Kirchhoff's rules for electrical networks. Write down the underlying conservation law on which each of these two rules is based.

Accepted Answer

Kirchhoff's rules are essential for analyzing complex electrical circuits where Ohm's law alone is insufficient. There are two primary rules: Kirchhoff's Current Law (KCL or Junction Rule): This rule states that the algebraic sum of all electric currents meeting at any junction in a closed electrica

Question 3

Explain the principle, construction, working, and uses of a potentiometer. Derive the formula used to compare the emfs of two primary cells using a potentiometer.

Accepted Answer

Principle of Potentiometer The potentiometer works on the principle that the potential drop across any portion of a wire of uniform cross-section and constant composition is directly proportional to the length of that portion, provided a steady current flows through it. $$V propto l implies V = k cd

Question 4

Define drift velocity of free electrons in a conductor. Establish the relation between electric current and drift velocity, and hence deduce Ohm's law at the microscopic level.

Accepted Answer

Definition of Drift Velocity Drift Velocity ($vd$): It is defined as the average velocity with which free electrons get drifted towards the positive terminal of a conductor under the influence of an applied external electric field. The magnitude of drift velocity is typically of the order of $10^{-4

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