Electric Power

  1. Electric power is the rate at which electrical energy is consumed or produced in a circuit.
  2. The formula for electric power is P = VI, where P is power, V is voltage, and I is current.
  3. Using Ohm’s law, power can also be expressed as P = I²R or P = V²/R, where R is resistance.
  4. Its SI unit is the watt (W), where 1 watt = 1 joule/second.
  5. In household applications, power is often measured in kilowatts (kW).
  6. The energy consumed is given by Energy = Power × Time and is measured in kilowatt-hours (kWh).
  7. Higher power ratings indicate greater energy consumption or generation.
  8. Electric power is used in devices like motors, heaters, and lighting.

Heating Effect of Current

  1. The heating effect of current is the production of heat when an electric current flows through a conductor.
  2. This effect is due to the resistance of the conductor, which opposes the flow of current.
  3. The heat produced is given by H = I²Rt, where H is heat, I is current, R is resistance, and t is time.
  4. The heating effect is used in devices like electric heaters, toasters, and irons.
  5. Conductors with high resistance produce more heat for the same current.
  6. The heating effect of current is the basis of the Joule's law of heating.
  7. Excessive heating can damage circuits, so fuses and circuit breakers are used for protection.

Applications of Heating Effect

  1. Electric heating is used in resistive elements like filament lamps.
  2. Fuses are based on the heating effect, melting when current exceeds a certain limit.
  3. Electric cooking appliances like ovens and stoves utilize the heating effect.
  4. In welding, the heat generated by current is used to fuse materials together.
  5. Thermal sensors and devices like thermistors are designed to exploit the heating effect.

Key Points

  1. Both power and heat depend on the amount of current and resistance in the circuit.
  2. Efficient energy usage requires minimizing resistance to reduce unwanted heat loss.
  3. The efficiency of electrical devices is determined by the ratio of useful power output to total power input.
  4. Overheating can be mitigated using heat sinks and proper insulation in circuits.
  5. Electric power generation in power plants is transmitted over long distances with minimal loss by using high voltage and low current.
  6. Understanding the heating effect is crucial in designing safe and efficient electrical systems.

Category

Questions

  1. What is the formula for electric power?
  2. What is the SI unit of electric power?
  3. How is electric power related to resistance and current?
  4. Which law explains the heating effect of current?
  5. What happens to the power if the voltage is doubled while resistance remains constant?
  6. What does Joule’s law state?
  7. What is the relation between power, voltage, and resistance?
  8. What is the energy consumed by a device operating at 100 W for 2 hours?
  9. Which of the following is not an application of the heating effect of current?
  10. What is the power dissipated in a resistor of 5 ohms carrying 2 A of current?
  11. Which of the following appliances works on the heating effect of current?
  12. How is the heat produced in a resistor related to time?
  13. If a 60 W bulb operates for 10 hours, what is the total energy consumed?
  14. What is the heating effect of current dependent on?
  15. What happens to the resistance of a wire when its temperature increases?
  16. What happens to the heat produced if the resistance in a circuit is halved?
  17. What is the relationship between electric power and energy?
  18. What is the formula for calculating energy in terms of power and time?
  19. What happens to the power dissipation if the current in a circuit is doubled?
  20. Which of the following is a practical application of Joule heating?
  21. What happens to the heat generated in a resistor if both the current and resistance are doubled?
  22. Which quantity is directly proportional to the heating effect of current?
  23. What happens to the energy consumption when an electric device is used for twice the time?
  24. What is the power of a device that draws 2 A of current at 220 V?
  25. Which factor does not affect the heating effect of current?
  26. How is the heat generated in a conductor related to its material?
  27. What happens to the heating effect in a conductor if its length is doubled?
  28. What is the power rating of an electric iron if it uses 1.5 kWh in 3 hours?
  29. Which of the following is a unit of energy?
  30. What is the total energy consumed by a 1 kW heater running for 5 hours?
  31. What happens to the power dissipation in a circuit when voltage and current are both halved?
  32. If a resistor dissipates 50 W of power at 10 V, what is its resistance?
  33. What is the SI unit of energy consumed in electrical circuits?
  34. What is the effect of using a fuse with a higher current rating than required?
  35. Which electrical appliance is based on the heating effect of current?
  36. What is the relationship between resistance and heat produced in a wire?
  37. What happens to the heating effect in a circuit if the current is tripled?