JAMB Physics questions: Magnets and magnetic fields

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

1. Question 1· Magnets and magnetic fields· JAMB

   Soft iron is used in electromagnets because it

   • Akeeps its magnetism permanently
   • Bis easily magnetised and demagnetised
   • Cis non-magnetic
   • Ddoes not conduct

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   Explanation and discussion

2. Question 2· Magnets and magnetic fields· JAMB

   At the magnetic equator, the angle of dip is

   • A90°
   • B0°
   • C45°
   • D180°

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   Explanation and discussion

3. Question 3· Magnets and magnetic fields· JAMB

   The north pole of a freely suspended magnet points approximately towards the Earth's

   • Aeast
   • Bgeographic south
   • Cgeographic north
   • Dwest

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   Explanation and discussion

4. Question 4· Magnets and magnetic fields· JAMB

   The angle of dip at the magnetic equator is

   • A0°
   • B90°
   • C45°
   • D180°

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   Explanation and discussion

5. Question 5· Magnets and magnetic fields· JAMB

   The magnetic field round a straight current-carrying wire consists of

   • Ano field at all
   • Bstraight lines parallel to the wire
   • Cradial lines from the wire
   • Dconcentric circles round the wire

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6. Question 6· Magnets and magnetic fields· JAMB

   The best way to demagnetise a bar magnet is to

   • Akeep it with keepers
   • Bplace it in a solenoid carrying direct current
   • Cstroke it with another magnet
   • Dplace it in a solenoid carrying alternating current and slowly withdraw it

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7. Question 7· Magnets and magnetic fields· JAMB

   The angle between the geographic meridian and the magnetic meridian is called the

   • Aangle of inclination
   • Bangle of dip
   • Cangle of declination
   • Dcritical angle

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   Explanation and discussion

8. Question 8· Magnets and magnetic fields· JAMB

   Outside a bar magnet, magnetic field lines run from

   • Athe north pole to the south pole
   • Bthe south pole to the north pole
   • Cthe middle to the ends
   • Dnowhere; there are no field lines

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   Explanation and discussion

9. Question 9· Magnets and magnetic fields· JAMB

   Soft iron is used as the core of an electromagnet because it

   • Ais easily magnetised and demagnetised
   • Bkeeps its magnetism permanently
   • Cis a good conductor of heat
   • Dis very hard

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10. Question 10· Magnets and magnetic fields· JAMB

    Which group of metals is strongly magnetic?

    • Asilver, sodium and calcium
    • Bcopper, zinc and tin
    • Caluminium, lead and gold
    • Diron, nickel and cobalt

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11. Question 11· Magnets and magnetic fields· JAMB

    Soft iron keepers are placed across the poles of stored magnets in order to

    • Areverse the poles
    • Bincrease their weight
    • Cmake them magnetic
    • Dprevent self-demagnetisation

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12. Question 12· Magnets and magnetic fields· JAMB

    A neutral point in a magnetic field is a point where

    • Aonly the Earth's field acts
    • Bthe field is strongest
    • Cthe resultant magnetic field is zero
    • Dthe needle points north

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    Explanation and discussion