JAMB and WAEC Physics questions

829 questions with answers and explanations. Tap an option to check yourself.

1. Question 201· Electromagnetic induction· WAEC

   A step-up transformer has 50 turns on its primary and 1,000 turns on its secondary. Find the output for a 12 V input.

   • A240 V
   • B0.6 V
   • C600 V
   • D12 V

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2. Question 202· Electromagnetic induction· JAMB

   A step-down transformer changes 240 V to 12 V. If the primary coil has 2000 turns, how many turns has the secondary?

   • A200
   • B40 000
   • C100
   • D20

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3. Question 203· Electromagnetic induction· WAEC

   A transformer has 100 turns on the primary coil and 500 turns on the secondary. If the primary voltage is 20 V, the secondary voltage is

   • A4 V
   • B100 V
   • C2,500 V
   • D400 V

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4. Question 204· Electromagnetic induction· JAMB

   An a.c. generator differs from a d.c. generator mainly in having

   • Ano coil
   • Bslip rings instead of a split-ring commutator
   • Cno magnet
   • Diron brushes

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5. Question 205· Electromagnetic induction· JAMB

   An a.c. generator converts

   • Achemical energy into electrical energy
   • Belectrical energy into mechanical energy
   • Cheat into light
   • Dmechanical energy into electrical energy

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6. Question 206· Electromagnetic induction· WAEC

   Lenz's law is a consequence of the conservation of

   • Amomentum
   • Bmass
   • Ccharge
   • Denergy

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7. Question 207· Electromagnetic induction· JAMB

   A transformer that is 90% efficient delivers 180 W. Find its input power.

   • A162 W
   • B200 W
   • C180 W
   • D270 W

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8. Question 208· Electromagnetic induction· JAMB

   The direction of an induced current is given by:

   • ALenz's law
   • BFleming's left-hand rule
   • COhm's law
   • DCoulomb's law

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9. Question 209· Electromagnetic induction· WAEC

   A dynamo converts

   • Amechanical energy into electrical energy
   • Belectrical energy into mechanical energy
   • Cheat into light
   • Dchemical energy into electrical energy

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10. Question 210· Electromagnetic induction· JAMB

    Energy losses due to eddy currents in a transformer core are reduced by

    • Ausing thicker wire
    • Blaminating the core
    • Cusing a solid iron core
    • Dincreasing the voltage

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11. Question 211· Electromagnetic induction· JAMB

    Faraday's law states that the induced e.m.f. in a circuit is proportional to the

    • Anumber of cells
    • Bstrength of the magnet only
    • Cresistance of the circuit
    • Drate of change of magnetic flux linkage

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12. Question 212· Electromagnetic induction· JAMB

    A transformer does not work with a steady direct current because

    • Ad.c. overheats the core
    • Bd.c. is too weak
    • Ca steady current produces no changing magnetic flux
    • Dthe coils would melt

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13. Question 213· Electromagnetic induction· JAMB

    A transformer works on the principle of

    • Amutual induction
    • Bself-induction only
    • Cthe heating effect of current
    • Delectrolysis

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14. Question 214· Electromagnetic induction· JAMB

    Electric power is transmitted over long distances at very high voltage mainly to

    • Amake the cables lighter
    • Bincrease the current
    • Creduce energy lost as heat in the cables
    • Dincrease the frequency

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15. Question 215· Electromagnetic induction· JAMB

    A transformer steps 240 V down to 12 V. If the secondary coil has 50 turns, the primary has

    • A2.5 turns
    • B1,000 turns
    • C20 turns
    • D50 turns

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16. Question 216· Electromagnetic induction· WAEC

    A transformer has 200 turns in its primary and 1000 turns in its secondary. If 12 V a.c. is applied, find the output voltage.

    • A60 V
    • B2.4 V
    • C12 V
    • D240 V

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17. Question 217· Electromagnetic induction· WAEC

    A transformer works only with alternating current because

    • Ad.c. damages the core
    • Bd.c. is too strong
    • Ca.c. has no voltage
    • Dit needs a changing magnetic flux

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18. Question 218· Electrostatics· JAMB

    On a charged conductor, charge collects mainly

    • Aon the outer surface, especially at sharp points
    • Bat its centre
    • Cin its inner core
    • Dnowhere

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19. Question 219· Electrostatics· WAEC

    The instrument used to detect and test small electric charges is the

    • Agalvanometer
    • Bgold-leaf electroscope
    • Cammeter
    • Dvoltmeter

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20. Question 220· Electrostatics· JAMB

    Two charges of 2 μC each are 0.3 m apart. Find the force between them. (k = 9 × 10⁹ N m²/C²)

    • A1.2 × 10⁻⁵ N
    • B0.12 N
    • C4 N
    • D0.4 N

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