Current Electricity

 Section A: Objective Type Questions

  1. Electric current is a scalar quantity. (True/False)
  2. According to Ohm's law, the ratio of voltage to current is constant for a given conductor. (True/False)
  3. The resistivity of a conductor depends on its length, cross-sectional area, and temperature. (True/False)
  4. The resistance of a conductor increases with an increase in its cross-sectional area. (True/False)
  5. The potential difference across a resistor is directly proportional to the current flowing through it. (True/False)
  6. Kirchhoff's first law is a consequence of the law of conservation of energy. (True/False)
  7. A potentiometer is a device used to measure the resistance of a conductor. (True/False)
  8. The time constant of an RC circuit depends on the resistance and capacitance of the circuit. (True/False)
  9. Joule's law of heating states that the heat generated in a conductor is directly proportional to the square of the current flowing through it. (True/False)
  10. A cyclotron is a device used to generate magnetic fields. (True/False)

Section B: Short Answer Type Questions

  1. State Ohm's law. Derive its mathematical expression.
  2. Define resistivity and state its SI unit. Explain how it is related to the conductivity of a material.
  3. Explain the concept of internal resistance of a cell and how it affects the output voltage of the cell.
  4. State Kirchhoff's laws and explain their significance in current electricity.
  5. Derive the expression for the capacitance of a parallel-plate capacitor in terms of its area, separation, and dielectric constant.

Section C: Long Answer Type Questions

  1. Derive the expression for the resistance of a conductor in terms of its length, cross-sectional area, and resistivity. How does the resistance of a wire change with temperature?
  2. Explain the phenomenon of drift velocity and derive its expression in terms of electric field, relaxation time, and mobility of charge carriers.
  3. Describe the construction and working of a meter bridge. How is it used to measure the resistance of a conductor?
  4. Explain the principle of a potentiometer and how it can be used to measure the emf of a cell.
  5. Define the term 'magnetic field' and explain how it is related to the current flowing through a conductor. Explain the working principle of a cyclotron and how it is used to accelerate charged particles.