Electric Potential

  1. Electric potential is the amount of work done to bring a unit positive charge from infinity to a point in an electric field.
  2. It is a scalar quantity and is measured in volts (V).
  3. The formula for electric potential due to a point charge is \( V = k \frac{q}{r} \), where \( q \) is the charge and \( r \) is the distance.
  4. The reference potential is usually taken as zero at infinity.
  5. Positive charges create regions of high potential, and negative charges create regions of low potential.
  6. Electric potential is related to the electric field by \( E = -\frac{dV}{dx} \), where \( E \) is the field and \( V \) is the potential.

Potential Difference

  1. Potential difference is the work done to move a unit charge between two points in an electric field.
  2. It is also measured in volts (V).
  3. The formula is \( V = W/q \), where \( W \) is the work done, and \( q \) is the charge.
  4. Potential difference drives the flow of charges in a circuit (electric current).
  5. It is the cause of the electric current in conductors and is maintained by sources like batteries or generators.

Capacitors

  1. A capacitor is a device used to store electric charge and energy.
  2. The capacity of a capacitor is measured by its capacitance, which is the charge stored per unit potential difference: \( C = Q/V \).
  3. The unit of capacitance is the farad (F).
  4. The simplest type is the parallel plate capacitor, consisting of two conductive plates separated by an insulating material (dielectric).
  5. The formula for capacitance of a parallel plate capacitor is \( C = \epsilon_0 \frac{A}{d} \), where \( A \) is the area of plates and \( d \) is the distance between them.
  6. Dielectric materials increase the capacitance by reducing the effective electric field between the plates.
  7. The energy stored in a capacitor is given by \( U = \frac{1}{2}CV^2 \).

Key Concepts

  1. Electric potential and potential difference are essential for understanding electrical circuits and energy transfer.
  2. Capacitors are used in timing circuits, energy storage, and filtering signals in electronics.
  3. Capacitors with variable capacitance are used in tuning circuits, such as radios.
  4. The concept of electric potential is crucial in understanding phenomena like lightning and electric discharge.
  5. High-capacity capacitors are used in defibrillators for medical applications.
  6. Potential difference is fundamental for understanding the operation of batteries and generators.

Category

Questions

  1. What is the charge stored in a capacitor when connected to a battery?
  2. Which of the following devices stores electric energy?
  3. What happens to the capacitance if the distance between the plates is halved?
  4. What is the energy density in a capacitor proportional to?
  5. What is the potential difference across a capacitor given by?
  6. What happens to the capacitance of a capacitor when the dielectric constant increases?
  7. What is the work done to move a charge in an equipotential surface?
  8. What is the capacitance of a spherical capacitor proportional to?
  9. The electric potential at a point in space is defined as what?
  10. What is the unit of electric potential energy?
  11. What is the potential of the Earth considered to be?
  12. Which factor does not affect the capacitance of a capacitor?
  13. What happens to the energy stored in a capacitor if the voltage is doubled?
  14. If a capacitor is connected to a battery, what remains constant?
  15. How is energy stored in a capacitor calculated?
  16. What is the equivalent capacitance of capacitors connected in parallel?
  17. How does the addition of a dielectric material affect the capacitance of a capacitor?
  18. What is the equivalent capacitance of capacitors connected in series?
  19. What is the capacitance of a parallel plate capacitor proportional to?
  20. What is the potential energy stored in a capacitor given by?
  21. What is the function of a dielectric in a capacitor?
  22. How does capacitance change if the distance between capacitor plates is doubled?
  23. What happens to the capacitance if the area of the plates of a capacitor is doubled?
  24. What is the SI unit of capacitance?
  25. What is the relation between electric field (E) and potential (V)?
  26. The electric potential at a point due to a point charge is inversely proportional to what?
  27. What is the potential difference between two points in an electric field?
  28. What is the SI unit of electric potential?
  29. How is electric potential defined?
  30. A capacitor with air as a dielectric has capacitance C. What happens if the air is replaced by a material of dielectric constant k?
  31. If two capacitors are connected in series, what is true about their charges?
  32. What is the unit of potential gradient?
  33. What happens to the potential at a point if the charge is doubled?
  34. What type of energy is stored in a capacitor?