EXAMPLE_flux

1

Q1

A uniform magnetic field of 0.35 T in the vertical
direction exists. A piece of cardboard with a
surface area of 0.35 m2 is placed flat on a
horizontal surface inside the field.

a) What is the magnetic flux through the
cardboard?
b) The one edge is then lifted so that the
cardboard is now inclined at 17° to the positive x-
direction. What is the magnetic flux through the
cardboard?

Example for Solution

(a)
1. List the information given;

A = 0.35 m2 A
B = 0.35 T
∅=0

B

2. Choose a suitable formula :

∅ =

3. Apply the formula.

=
= 0.35 0.35 cos(0)
= 0.1225

Example for Solution

(b)

1. List the information given;

A = 0.35 m2 AB
B = 0.35 T
∅ = 17°

2. Choose a suitable formula :

∅ =

3. Apply the formula.

=
= 0.35 0.35 cos(17)
= 0.117

Q2

Total number of magnetic
field lines passing through an
area is called

a)magnetic flux density
b)magnetic flux
c)e.m.f
d)voltage

Example for Solution

Total number of magnetic field
lines passing through an area is
called

a) magnetic flux density
b) magnetic flux
c) e.m.f
d) voltage

Q3

A square loop of wire 9.0 cm
on a side is in 2.4 T magnetic
field.

Calculate the maximum and
minimum values of the
magnetic flux that can pass
through the loop?

Example for Solution

1. List the information given;

A = 9.0x9.0 cm2
B = 2.4 T

2. Choose a suitable formula :

∅ =

3. Apply the formula.

Important to consider:
Maximum value,

cos = cos 0 = 1
cos = cos 0 = −1

Thus, the value of maximum flux is

∅ = 2.4 0.09 cos 0
∅ = 1.94 × 10−2
∅ = −1.9O4R× 10−2

Important to consider:
Minimum value,

cos = cos 90 = 0

Thus, the value of minimum flux is

∅ = 2.4 0.09 cos 90
∅ = 0

Q43

A uniform magnetic field of 5T in
the vertical direction exists.

What is the magnetic flux through
a horizontal circle of radius 0.68 m
if placed perpendicular to the
magnetic field?

Example for Solution

1. List the information given;

A for =circle π 2 A
= π(0.68)2

B=5T

B

2. Choose a suitable formula :

∅ =

3. Apply the formula.

=
= (5) 0.68 2cos(0)
= 7.26

Q45

A uniform magnetic field of 0.5 T
in the vertical direction exists.
200 turns of coils with surface
area 0.25 m2 is placed incline 30°
to the positive x-direction of a
horizontal surface inside the field.

What is the magnetic flux?

Example for Solution

1. List the information given;

A = 0.25 2 A
B = 0.5 T
∅ = 30°

B

2. Choose a suitable formula :

∅ =

3. Apply the formula.

=
= 200 0.5(0.25)cos(30)
= 3.856