Magnets and Magnetic Fields - Jamb Physics Past Questions and Answers

Question 21:

• JAMB 1989

When a number of identical small magnets are arranged in a line, the strength of the resultant magnet

A. Ia largest when they are arranged end to end
B. Is greatest when they are arrangedparallel with like poles adjacent to each other
C. Depends only on the number of magnets provided they arev parallel
D. Is greater when the magnets are arranged on a wooden surface than on a metaln surface

Question 22:

• JAMB 1989

A bar magnet is most effectively demagnetized by

A. Placing it in a N - 5 position and hitting it with a hammer
B. Subjecting it to an electric current from a battery
C. Bringing its north pole in contact with the north pole of a very strong magnet
D. Heating the magnet

Question 23:

• JAMB 1989

The fig above shows a conductor PQ carrying a current I in the direction shown. At a particular position near the conductor is a compass needle K. Neglecting the earth's magnetic field, the compass needle will

A. Settle in any direction
B. Settle in a fixed direction only if the conductor PQ is a magnetic material
C. Settle in a fixed direction WHETHER the conductor PQ is a magnetic material OR NOT
D. Be stationary

Question 24:

• JAMB 1990

One of the properties of the earth's magnetic field is that the

A. North pole lies in the northern hemisphere
B. Geographic and magnetic meridians coincide
C. Earth's magnetic flux is entirely horizontal at a place where the magnetic dip is zero
D. Earth's magnetic flux is entirely vertical at a place where the magnetic dip is zero

Question 25:

• JAMB 1991

Which of the following statements is CORRECT about the earth's magnetic field?

A. The angle of dip is the angle which a freely suspended magnet makes with the vertical
B. The angle of declination is the angle between the magnetic meridian and the geographic meridian
C. The angle of declination is the angle which a magnetic compass makes with the magnetic meridian
D. The angle of inclination is the difference between the angle of dip and the angle of declination