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12th Standard Physics Current Electricity English Medium Free Online Test One Mark questions 2020 - 2021

12th Standard

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Physics

Time : 00:20:00 Hrs
Total Marks : 20
    Answer all the questions
    20 x 1 = 20
  1. Th e following graph shows current versus voltage values of some unknown conductor. What is the resistance of this conductor?

    (a)

    2 ohm

    (b)

    4 ohm

    (c)

    8 ohm

    (d)

    1 ohm

  2. A toaster operating at 240 V has a resistance of 120 Ω. Th e power is

    (a)

    400 W

    (b)

    2 W

    (c)

    480 W

    (d)

    240 W

  3. What is the value of resistance of the following resistor?

    (a)

    100 k Ω

    (b)

    10 k Ω

    (c)

    1k Ω

    (d)

    1000 k Ω

  4. A wire connected to a power supply of 230 V has power dissipation P1. Suppose the wire is cut into two equal pieces and connected parallel to the same power supply. In this case power dissipation is P2. The ratio \(\frac{P_2}{P_1}\) is

    (a)

    1

    (b)

    2

    (c)

    3

    (d)

    4

  5. In a large building, there are 15 bulbs of 40W, 5 bulbs of 100W, 5 fans of 80W and 1 heater of 1kW are connected. The voltage of electric mains is 220V. The minimum capacity of the main fuse of the building will be

    (a)

    14 A

    (b)

    8 A

    (c)

    10 A

    (d)

    12 A

  6. The internal resistance of a 2.1 V cell which gives a current of 0.2 A through a resistance of 10 Ω is

    (a)

    0.2 Ω

    (b)

    0.5 Ω

    (c)

    0.8 Ω

    (d)

    1.0 Ω

  7. The colour code on a carbon resistor is red - red - black. The resistance of the resistor is?

    (a)

    \(2.2\Omega \)

    (b)

    \(22\Omega \)

    (c)

    \(220\quad 2.2\Omega \)

    (d)

    \(2.2k\Omega \)

  8. When 'n' resistors of equal resistance (R) are connected in series and in parallel respectively,then the ratio of their effective resistance is

    (a)

    1: n2

    (b)

    n2: 1

    (c)

    n: 1

    (d)

    1: n

  9. The resistance of the wire varies inversely as

    (a)

    area of cross section

    (b)

    resistivity

    (c)

    length

    (d)

    temperature

  10. Calculate the mobility of a free electron in an electric field of 10+2N/C.

    (a)

    10-4m2V-1s-1

    (b)

    10-5m2V-1s-1

    (c)

    10-3m2V-1s-1

    (d)

    105m2V-1s-1

  11. Carbon are furnaces produce temperature upto________

    (a)

    1500oC

    (b)

    2000o C

    (c)

    2500oC

    (d)

    3000oC

  12. The unit of current density is________

    (a)

    Am-2

    (b)

    Am2

    (c)

    A2m-2

    (d)

    A-2m-2

  13. The reciprocal of conductivity is________

    (a)

    specific conductance

    (b)

    specific resistance

    (c)

    resistance

    (d)

    conductance

  14. The transition temperature of mercury is________

    (a)

    4.2°C

    (b)

    4.2 K

    (c)

    2.4°C

    (d)

    2.4K

  15. In a carbon resistor, the third ring represents___________

    (a)

    powers of zeros

    (b)

    powers of ten

    (c)

    ten

    (d)

    infinity

  16. The temperature coefficient of resistance is negative for_________

    (a)

    for metals

    (b)

    ebonite

    (c)

    (a) and (b)

    (d)

    none

  17. Ohm's law is applicable only for_______________

    (a)

    complicated circuits

    (b)

    primary circuits

    (c)

    simple circuits

    (d)

    secondary circuits

  18. In Kirchhoff's II law) the current in clockwise direction is taken as________

    (a)

    positive

    (b)

    negative

    (c)

    neutral

    (d)

    no direction

  19. In the case of meter bridge) manganin wire is used because it has_________

    (a)

    low temperature co~fficient of resistance

    (b)

    high temperature coefficient of resistance

    (c)

    temperature coefficient of resistance is zero

    (d)

    temperature coefficient of resistance is maximum

  20. Potentiometer is an instrument used for the measurement of____________

    (a)

    current

    (b)

    resistance

    (c)

    capacitance

    (d)

    potential difference

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