Electricity in Science

Updated on May 31, 2025 | By Learnzy Academy

Electricity is the flow of electric charge that powers devices and makes things work.

Important Parts of Electricity:

  1. Electric Current: The flow of electric charge, measured in Amps (A).
  2. Voltage: The force that pushes the electric charge, measured in Volts (V).
  3. Resistance: The opposition to the flow of current, measured in Ohms (Ω).
  4. Ohm's Law:  V = I × R – Voltage = Current × Resistance.
  5. Power: The amount of energy used, calculated by P = V × I (measured in Watts).

Types of Current:

  1. DC (Direct Current): Flows in one direction (like from a battery).
  2. AC (Alternating Current): Reverses direction (like in home electricity).
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List of question on "Electricity"

  1. What determines the rate at which energy is delivered by a current?
  2. An electric iron of resistance 20 Ω takes a current of 5 A. Calculate the heat developed in 30 s.
  3. Compute the heat generated while transferring 96000 coulomb of charge in one hour through a potential difference of 50 V
  4. Why does the cord of an electric heater not glow while the heating element does?
  5. What are the advantages of connecting electrical devices in parallel with the battery instead of connecting them in series?
  6. Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?
  7. Let the resistance of an electrical component remains constant while the potential difference across the two ends of the component decreases to half of its former value. What change will occur in the current through it?
  8. Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?
  9. On what factors does the resistance of a conductor depend?
  10. What is meant by saying that the potential difference between two points is 1 V?
  11. Name a device that helps to maintain a potential difference across a conductor.
  12. Calculate the number of electrons constituting one coulomb of charge.
  13. Define the unit of current.
  14. What does an electric circuit mean?
  15. How much energy is given to each coulomb of charge passing through a 6 V battery?
  16. What is the maximum resistance which can be made using five resistors each of 1/5 Ω ?
  17. A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross section of the filament in 16 seconds would be roughly.
  18. Calculate the resistivity of the material of a wire of length 1 m, radius 0.01 cm and resistance 20 ohms.
  19. List the factors on which the resistance of a conductor in the shape of a wire depends.
  20. Why are alloys commonly used in electrical heating devices ?
  21. Why are metals good conductors of electricity whereas glass is a bad conductor of electricity ? Give reason.
  22. Calculate the resistance of a metal wire of length 2 meters and cross-sectional area 1.55 × 10⁻⁶ square meters, if the resistivity of the metal is 2.8 × 10⁻⁸ ohm meter.
  23. How is the resistivity of alloys compared with those of pure metals from which they may have been formed?
  24. Name a device that you can use to maintain a potential difference between the ends of a conductor. Explain the process by which this device does so.