1. What is electromagnetic field?
Answer: Electromagnetic field is region where both electric force and magnetic force are felt by charged particles.
2. What is the total force of electromagnetic field?
Answer: the total force F of electromagnetic field is given by the vector sum of electric and magnetic forces. Fe and Fm respectively. That is
F = Fe + Fm
F = q(E + v x B)
3. The force experienced by a current carrying conductor of length 100cm is 2.0N. Calculate the current in the conductor if it is flowing in 450 direction, with the field of 1.0 tesla.
Answer: Using F = BILsinѲ
Where F = Force =2.0N, B=Magnetic flux density of the field = 1.0 tesla or 1.0T Ѳ =450, L = length of the conductor = 100cm =1m
Therefore F= BILsinѲ is given as
2 = 1 x 1 x I x sin450
I = 2/sin450 =2.83A
The current = 2.83A.
4. Calculate the force on a charge +2ɥC moving with a velocity 2 x 106m/s in a field of magnetic flux density 0.5T
(i). For Parallel field
(ii) For perpendicular field
F = qvBsinѲ,
where q = charges = +2ɥC, V= velocity of the charge in the field = 2 x 106m/s, B = magnetic flux density = 0.5T, Ѳ = 900 for perpendicular field and Ѳ = 00 for parallel field.
So for (i). Parallel field is given as
F = 2 x 10-6 x 2 x 106 x 0.5 x sin0 = 0 since Ѳ = 0 for parallel field
For (ii) Perpendicular field
F = 2 x 10-6 x 2 x 106 x 0.5 x sin90
F = 2 x 10-6 + 6 x 0.5 x 1
F = 2 x 10 x 0.5
F = 20 x 0.5 = 2N
So for (ii) Perpendicular field F = 2N
5. What is magnetic flux?
Answer: The magnetic flux is the line of force of magnetic field. The unit is webers (Wb). It is given as
Φ = ABcosѲ, where Φ = magnetic flux, A =area of the surface at right angles to the field, B = magnetic flux density.