Electricity Assignment -2

  1. What is meant by “electrical resistance” of a conductor? State how resistance of a conductor is affected when (i) a low current passes through it for a short duration; (ii) a heavy current passes through it for about 30 seconds.
  2. How is the resistivity of alloys compared with those of pure metals from which they have been formed?
  3. What is meant by saying that the potential difference between the two points is one volt ?
  4. Define 1 ohm resistance
  5. What is the SI unit of resistivity. What is the difference between resistance and resistivity.
  6. What is meant by an electric circuit?
  7. A bulb can not be used in place of a resistor to verify ohms law. Justify this statement with reason. (2)
  8. State Ohm’s law . Describe an activity to verify ohm’s law   (4)
  9. A wire is stretched to 4 times its length. What will be the change in resistance . Show with calculations(3)
  10. When  a  12  V  battery  is  connected  across  an  unknown  resistor,  2.5 mA current flows in the circuit. Find the resistance of the resistor (2)
  11. What  is meant  by  “electric  resistance”  of  a  conductor?  How  is  it  determined?  Name  and define its SI unit. (4)
  12. What is meant by potential difference between two points in an electric circuit? Name its SI unit. Write the name of the instrument used to measure potential difference and show with diargram how this instrument is connected in a circuit. (4)
  13. Define  1  volt.   Calculate  the  amount  of  energy consumed in carrying a charge of 1 coulomb through a battery of 3 volts. (3)
  14. Is potential difference scalar or vector quantity ? (1)
  15. In a conductor electrons are flowing from B to A ? What is the direction of conventional current  (1)
  16. Name a device that helps to maintain a potential difference across a conductor.(1)
  17. Draw a schematic diagrams of an electric circuit comprising of 3 cells and an electric bulb, ammeter, plug-key in the ON mode and another with same components but with two bulbs in parallel and a voltmeter across the combination. (3)
  18. Calculate the number of electrons in 1 Coulomb of Charge (2)
  19. What is an electric circuit? Distinguish between an open and a closed circuit. (2)
  20. Define the term ‘coulomb’. (1)
  21. 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? (2)
  22. A given length of a wire is doubled on itself and this process is repeated once again. By what factor does the resistance of the wire change? (2)