Tutorial 2: Magnetism
1.What is the electromagnetism?
2. Explain the Laws of Magnetism and give the example on demonstration of
these laws.
- i) Like poles repel each other
- ii) Unlike poles attract each other
3. Given two sets of magnetic bars. Sketch the magnetic fields for each of them.
S
N
N
S
S
N
S
N
4. Explain the right hand rule.
5. In the special case where the surface S is a planar surface with area A, and
the magnetic field is constant with magnitude B, the formula simplifies to
where θ is the angle between B and the surface normal to S.
A small surface of area 10mm2 inside a uniform magnetic field of strength 0.5 T is
inclined at an angle α to the direction of the field. Determine the magnetic flux
through the surface if
a) α = 0°
b) α = 30°
c) α = 90°
(Hints: α = 90° - θ)
6. Magnetic flux passing through a surface bounded by a coil links with the coil.
The linkage is the field lines that are ‘linking up’ all the turns of the coil. This
magnetic flux linkage is given by
Flux linkage,  = N = NBA cos θ
A circular coil has 10 turns and diameter 2.0 cm.It is placed in a uniform
magnetic field of strength 300 mT. The plane of the coil and the direction of the
field make an angle of 30°. Determine the magnetic flux linkage through the
coil.
A rectangular coil has 100 turns and dimensions of 2.0 cm X 3.0 cm. It is placed
in a uniform magnetic field strength 200 mT. The plane of the coil and the
direction of the field make an angle of 30°. Determine the magnetic flux linkage
through the coil.
7. Magnetic force on moving charge is given by;
F=qvB sin 
Which  is an angle between v and B
If a charge is traveling in a wire of length L, it can be written as;
F q
L
q
B sin   LB sin   ILB sin 
t
t
A 0.5m length of wire carries a 10A current perpenducular to a magnetic field.
Determine the magnetic flux density, B needed so that the force on the wire is
3N.
An electron travels at 107 ms-1 in the positive x direction. The magnetic flux
density is 1T in the positive y direction. Find the force on the electron.