### 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. F_{e} and F_{m} respectively. That is

F = F_{e} + F_{m}

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 45^{0} 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 =45^{0}, L = length of the conductor = 100cm =1m

Therefore F= BILsinѲ is given as

2 = 1 x 1 x I x sin450

I = 2/sin45^{0} =2.83A

The current = 2.83A.

#### 4. Calculate the force on a charge +2ɥC moving with a
velocity 2 x 10^{6}m/s in a
field of magnetic flux density 0.5T

(i). For Parallel field

(ii) For perpendicular field

**Answe**r: Using

F = qvBsinѲ,

where q = charges = +2ɥC, V= velocity of the charge in the
field = 2 x 10^{6}m/s, B = magnetic flux density = 0.5T, Ѳ = 90^{0 }for
perpendicular field and Ѳ = 0^{0} for parallel field.

So for (i). Parallel field is given as

F = 2 x 10^{-6} x 2 x 10^{6} x 0.5 x sin0 =
0 since Ѳ = 0 for parallel field

For (ii) Perpendicular field

F = 2 x 10^{-6} x 2 x 10^{6} 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.