Science and Technology I · Textbook solutions

Effects of Electric Current

Every solved example, exercise, and miscellaneous question — in the order the textbook teaches them. · 24 questions

Exercise

24 q
  1. Tell the odd one out. Give proper explanation.
    Ex Q1(a)
    Fuse wire, bad conductor, rubber gloves, generator.
  2. Ex Q1(b)
    Voltmeter, Ammeter, galvanometer, thermometer.
  3. Ex Q1(c)
    Loud speaker, microphone, electric motor, magnet.
  4. Explain the construction and working of the following. Draw a neat diagram and label it.
    Ex Q2(a)
    Electric motor
  5. Ex Q2(b)
    Electric Generator(AC)
  6. Ex Q3
    Electromagnetic induction means-
    1. A.
      Charging of an electric conductor.
    2. B.
      Production of magnetic field due to a current flowing through a coil.
    3. C.
      Generation of a current in a coil due to relative motion between the coil and the magnet.
    4. D.
      Motion of the coil around the axle in an electric motor.
  7. Ex Q4
    Explain the difference : AC generator and DC generator.
  8. Ex Q5
    Which device is used to produce electricity? Describe with a neat diagram.
    1. A.
      Electric motor
    2. B.
      Galvanometer
    3. C.
      Electric Generator (DC)
    4. D.
      Voltmeter
  9. Ex Q6
    How does the short circuit form? What is its effect?
  10. Give Scientific reasons.
    Ex Q7(a)
    Tungsten metal is used to make a solenoid type coil in an electric bulb.
  11. Ex Q7(b)
    In the electric equipment producing heat e.g. iron, electric heater, boiler, toaster etc. an alloy such as Nichrome is used, not pure metals.
  12. Ex Q7(c)
    For electric power transmission, copper or aluminium wire is used.
  13. Ex Q7(d)
    In practice the unit kWh is used for the measurement of electrical energy, rather than joule.
  14. Ex Q8
    Which of the statement given below correctly describes the magnetic field near a long, straight current carrying conductor?
    1. A.
      The magnetic lines of force are in a plane, perpendicular to the conductor in the form of straight lines.
    2. B.
      The magnetic lines of force are parallel to the conductor on all the sides of conductor.
    3. C.
      The magnetic lines of force are perpendicular to the conductor going radially outward.
    4. D.
      The magnetic lines of force are in concentric circles with the wire as the center, in a plane perpendicular to the conductor.
  15. Ex Q9
    What is a solenoid? Compare the magnetic field produced by a solenoid with the magnetic field of a bar magnet. Draw neat figures and name various components.
  16. Name the following diagrams and explain the concept behind them.
    Ex Q10(a)
    The diagram shows a hand with the wrist at the right, held so that three of its parts are mutually perpendicular and an arrow is drawn along each: the forefinger stretched out towards the left, the thumb stretched upwards, and the middle finger stretched downwards.
  17. Ex Q10(b)
    The diagram shows a hand with the wrist at the left, held so that three of its parts are mutually perpendicular and an arrow is drawn along each: the forefinger stretched out towards the right, the thumb stretched upwards, and the middle finger stretched downwards.
  18. Identify the figures and explain their use.
    Ex Q11(a)
    The figure shows two short cylindrical cartridges lying side by side, each closed by a metal cap at either end - one having a transparent glass body through which a thin wire can be seen running end to end, and the other having an opaque red body.
  19. Ex Q11(b)
    The figure shows a panel-mounting device made of three identical units fixed side by side on a common base, each unit carrying a blue rocker switch marked OFF, with screw terminals along the top and the bottom edges.
  20. Ex Q11(c)
    The figure shows a rectangular coil held between two rectangular pole pieces placed one on either side of it. The two ends of the coil run down to a ring fitted on an axle, the ring being broken into two halves, and a stationary brush touches the ring on each side. The external circuit joining the two brushes contains an ammeter and no cell.
  21. Solve the following example.
    Ex Q12(a)
    Heat energy is being produced in a resistance in a circuit at the rate of 100 W. The current of 3 A is flowing in the circuit. What must be the value of the resistance?
  22. Ex Q12(b)
    Two tungsten bulbs of wattage 100 W and 60 W power work on 220 V potential difference. If they are connected in parallel, how much current will flow in the main conductor?
  23. Ex Q12(c)
    Who will spend more electrical energy? 500 W TV Set in 30 mins, or 600 W heater in 20 mins?
  24. Ex Q12(d)
    An electric iron of 1100 W is operated for 2 hrs daily. What will be the electrical consumption expenses for that in the month of April? (The electric company charges Rs 5 per unit of energy).