Work Power and Energy MCQ's

1. In the SI system of units, the unit of force is
    (a) kg-wt
    (b) newton
    (c) joule
    (d) N-m

2. The basic unit of electric charge is
    (a) ampere-hour
    (b) watt-hour
    (c) coulomb
    (d) farad

3. The SI unit of energy is
    (a) joule
    (b) KWH
    (c) kcal
    (d) m-kg

4. Two heating elements, each of 230V, 3.5 kw rating are first                joined in parallel and then in series to heat same amount of             water through the same range of temperature, The ratio of the           time taken in the two cases would be 
    (a) 1:2
    (b) 2:1
    (c) 1:4
    (d) 4:1

5. If a 220V heater is used on 110V supply, heat produced by it will     be -as much.
    (a) one-half
    (b) twice
    (c) one -fourth
    (d) four times

6. For a given line voltage, four heating coils will produce                   maximum heat when connected
    (a) all in parallel
    (b) all in series
    (c) with two parallel pairs in series
    (d) one pair in parallel with the other two in series

7. The electric energy required to raise the temperature of a given         amount of water is 1000 kwh. If heat losses are 25%, the total         heating energy required is _______ kwh.
    (a) 1500
    (b) 1250
    (c) 1333
    (d) 1000

8. One kwh of energy equals nearly
    (a) 1000 W
    (b) 860 kcal 
    (c) 4186 J
    (d) 735.5 W

9. One kwh of electric energy equals
    (a) 3600 J
    (b) 860 kcal
    (c) 3600 W
    (d) 4186 J

10. A 100 W light bulb burns on an average of 10 hours a day for           one week. The weekly consumption of energy will be                       _________ units.
     (a) 7
     (b) 70
     (c) 0.7
     (d) 0.07

11. Two heaters, rated at 1000 W, 250 volts each, are connected in         series across a 250 volts 50 Hz A.C. mains. The total power             drawn from the supply would be ________ watt. 
     (a) 1000
     (b) 500
     (c) 250
     (d) 2000