Problem-solving (Flux)

MAGNETIC FLUX 1

3-STEPS TO SOLVE
PROBLEM IN PHYSICS

List ALL the Choose a
value given in SUITABLE
formula.
SI units.

Substitute the
value into the

FORMULA.

Q1

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

a) magnetic induction
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 induction
b) Magnetic flux
c) E.M.F
d) Voltage

Q2

A piece of cardboard with a surface area of
0.35 m2 is placed flat on a horizontal surface in
an uniform magnetic field of 0.5 T in a vertical
direction upward.

a) What is the magnetic flux through the
cardboard?

b) One edge of the cardboard is then lifted
so that it inclined at 17° to the positive x-
direction. What is the magnetic flux through
the cardboard?

Example for Solution

(a)
1. Given;

A = 0.35 m2 A
B = 0.5 T
= 0°

B

2. Formula :

=

3. Apply :

=

= 0.5 0.35 cos(0)

= 0.175 Wb

Example for Solution

(b)

1. Given;

A = 0.35 m2 AB
B = 0.5 T 17°
= 17°

2. Formula :

=

3. Apply :

=
= 0.5 0.35 cos(17)

= 0.167 Wb

Q3

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

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

Example for Solution

1. Given;

A = length x length
= 9.0 x 9.0 cm2
= 8.1 x 10-3 m2

B = 2.4 T

2. Formula :

=

3. Apply :

Important to consider:
Maximum value when = 0° or 180°

cos = cos 0° = 1
= cos 180° = −1

Thus, the value of maximum flux is

= 2.4 8.1x 10−3 cos 0°
= 1.94 × 10−2 Wb

“-” Only show direction.

Important to consider:
Minimum value,

cos = cos 90° = 0

Thus, the value of minimum flux is

= 2.4 8.1x10−3 cos 90°
= 0 Wb

Q43

Determine the magnetic flux
passing through of a horizontal
circle with radius 0.68 m placed
perpendicular to a uniform
magnetic field of 5 T.

Example for Solution

1. Given : A

A for =circle π 2
= π(0.68)2

B=5T
= 0°

B

2. Formula :

=

3. Apply :

=
= (5) 0.68 2cos(0)

= 7.26 Wb

Q45

A uniform magnetic field of 0.5 T
in vertical direction exists. A 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 of the
coil?

Example for Solution

1. Given :

N = 200 turns
A = 0.25 m2 A
B = 0.5 T
= 30°

B

2. Formula :

=

3. Apply :

=
= 200 0.5(0.25)cos(30°)

= 21.65 Wb

Q46

A plane of a coil with radius of
0.2 m is located at 30° from 0.4 T
of a uniform magnetic field. What
is the magnetic flux through the
coil?

Example for Solution

1. Given : B
30° 60° A
r = 0.2 m

B = 0.4 T
= 60°

Remember angle must between normal
of area, A and B.

2. Formula :

=

3. Apply :

=
= 0.4( (0.22))cos(60°)

= 0.025 Wb)