SolveItClass 10 · NCERT

NCERT Solutions · Class 10 Science Electricity

18 questions · 18 still being checked

EXERCISES 11–18 (part 2 of 2)

  1. Exercise 11

    Show how you would connect three resistors, each of resistance 6\displaystyle 6 Ω, so that the combination has a resistance of
    (i)
    9\displaystyle 9 Ω, (ii) 4\displaystyle 4 Ω.

    Solution being prepared

  2. Exercise 12

    Several electric bulbs designed to be used on a 220\displaystyle 220 V electric supply line, are rated 10\displaystyle 10 W. How many lamps can be connected in parallel with each other across the two wires of 220\displaystyle 220 V line if the maximum allowable current is 5\displaystyle 5 A?
    NCERT’s answer
    $\displaystyle 110$ bulbs

    Working being prepared

  3. Exercise 13

    A hot plate of an electric oven connected to a 220\displaystyle 220 V line has two resistance coils A and B, each of 24\displaystyle 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?
    NCERT’s answer
    9.$\displaystyle 2$ A, $\displaystyle 4.6$ A, $\displaystyle 18.3$ A

    Working being prepared

  4. Exercise 14

    Compare the power used in the 2\displaystyle 2 Ω resistor in each of the following circuits:
    (i)
    a 6\displaystyle 6 V battery in series with 1\displaystyle 1 Ω and 2\displaystyle 2 Ω resistors, and
    (ii)
    a 4\displaystyle 4 V battery in parallel with 12\displaystyle 12 Ω and 2\displaystyle 2 Ω resistors.
    NCERT’s answer
    (i)
    $\displaystyle 8$ W;

    Working being prepared

  5. Exercise 15

    Two lamps, one rated 100\displaystyle 100 W at 220\displaystyle 220 V, and the other 60\displaystyle 60 W at 220\displaystyle 220 V, are connected in parallel to electric mains supply. What current is drawn from the line if the supply voltage is 220\displaystyle 220 V?
    NCERT’s answer
    0.$\displaystyle 73$ A

    Working being prepared

  6. Exercise 16

    Which uses more energy, a 250\displaystyle 250 W TV set in 1\displaystyle 1 hr, or a 1200\displaystyle 1200 W toaster in 10\displaystyle 10 minutes?
    NCERT’s answer
    $\displaystyle 250$ W TV set in $\displaystyle 1$ hour

    Working being prepared

  7. Exercise 17

    An electric heater of resistance 44\displaystyle 44 Ω draws 5\displaystyle 5 A from the service mains for 2\displaystyle 2 hours. Calculate the rate at which heat is developed in the heater.
    NCERT’s answer
    $\displaystyle 1100$ W

    Working being prepared

  8. Exercise 18

    Explain the following.
    (a)
    Why is the tungsten used almost exclusively for filament of electric lamps?
    (b)
    Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal?
    (c)
    Why is the series arrangement not used for domestic circuits?
    (d)
    How does the resistance of a wire vary with its area of cross-section?
    (e)
    Why are copper and aluminium wires usually employed for electricity transmission?
    NCERT’s answer
    (b)
    High resistivity of alloys

    Working being prepared