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برقیات اور مقناطیسیت

10 سوالات: ایم ڈی کیٹ طبیعیات، جوابات اور وضاحت کے ساتھ۔

تمام سوالات جوابات کے ساتھ
  1. A 12 V battery is connected across a 4 ohm resistor. What current flows?

    • 1 0.33 A
    • 2 3 A
    • 3 8 A
    • 4 48 A
    جواب دیکھیں

    درست جواب: 3 A

    By Ohm's law, I = V / R = 12 / 4 = 3 A.

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  2. Resistors of 2, 3 and 5 ohms are connected in series. What is the total resistance?

    • 1 0.97 ohm
    • 2 3.3 ohm
    • 3 10 ohm
    • 4 30 ohm
    جواب دیکھیں

    درست جواب: 10 ohm

    In series the resistances add: 2 + 3 + 5 = 10 ohm.

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  3. A 6 ohm and a 3 ohm resistor are connected in parallel. What is the equivalent resistance?

    • 1 2 ohm
    • 2 4.5 ohm
    • 3 9 ohm
    • 4 18 ohm
    جواب دیکھیں

    درست جواب: 2 ohm

    1/R = 1/6 + 1/3 = 3/6, so R = 2 ohm.

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  4. An appliance on 220 V draws 2 A. What is its power?

    • 1 110 W
    • 2 222 W
    • 3 440 W
    • 4 880 W
    جواب دیکھیں

    درست جواب: 440 W

    P = VI = 220 x 2 = 440 W.

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  5. The SI unit of capacitance is the:

    • 1 Henry
    • 2 Farad
    • 3 Tesla
    • 4 Weber
    جواب دیکھیں

    درست جواب: Farad

    Capacitance is measured in farads. The henry is for inductance, the tesla for magnetic field and the weber for magnetic flux.

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  6. The magnetic force on a moving charge is always:

    • 1 Parallel to its velocity
    • 2 Perpendicular to its velocity
    • 3 Opposite to its velocity
    • 4 Zero
    جواب دیکھیں

    درست جواب: Perpendicular to its velocity

    F = qvB sin θ acts at right angles to the velocity, so the force changes the direction of motion but not the speed.

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  7. A step-up transformer has:

    • 1 More turns in the primary coil
    • 2 More turns in the secondary coil
    • 3 Equal turns in both coils
    • 4 Only one coil
    جواب دیکھیں

    درست جواب: More turns in the secondary coil

    The output voltage is larger when the secondary has more turns than the primary.

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  8. Faraday's law of induction states that the induced emf is proportional to:

    • 1 The magnetic flux
    • 2 The rate of change of magnetic flux
    • 3 The resistance of the coil
    • 4 The charge on the coil
    جواب دیکھیں

    درست جواب: The rate of change of magnetic flux

    The induced emf depends on how fast the flux linked with the circuit changes.

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  9. How much electrical energy does a 2 kW heater use in 3 hours?

    • 1 1.5 kWh
    • 2 5 kWh
    • 3 6 kWh
    • 4 23 kWh
    جواب دیکھیں

    درست جواب: 6 kWh

    Energy = power x time = 2 kW x 3 h = 6 kWh.

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  10. Lenz's law is a consequence of the conservation of:

    • 1 Mass
    • 2 Charge
    • 3 Energy
    • 4 Momentum
    جواب دیکھیں

    درست جواب: Energy

    The induced current opposes the change that causes it. If it did not, energy would appear from nothing.

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