This material discusses about magnetic field and magnetic field occurs due to current

1. Presented by:
Erita Astrid, S.T., M.S
MEETING 9 &10
Magnetic Fields & Magnetic Fields Due To Current
eritaastrid@unimed.ac.id
FisikaElektrik
Friday, 8 Mei 2023

2. Magnetic Field
Magnetic Field is the region around a magnetic
material or a moving electric charge within which
the force of magnetism acts. It is a vector field
in the neighbourhood of a magnet, electric
current, or changing electric field in which
magnetic forces are observable.
 Magnetic field lines never cross each other
 The density of the field lines indicates the
strength of the field
 Magnetic field lines always make closed loops
 Magnetic field lines always emerge or start
from the north pole and terminate at the south
pole.

3. Electric Field & Magnetic Field
 Electric forces acting at a distance
through electric field.
 Vector field, E.
 Source: electric charge.
 Positive charge (+) and negative
charge (-).
 Opposite charges attract, like charges
repel.
 Electric field lines visualizing the
direction and magnitude of E.
 Magnetic forces acting at a distance
through Magnetic field.
 Vector field, B
 Source: moving electric charge
(current or magnetic substance,
such as permanent magnet).
 North pole (N) and south pole (S)
 Opposite poles attract, like poles
repel.
 Magnetic field lines visualizing the
direction and magnitude of B.

4. Definition of 𝐵

5. Magnetic Fields

6. Question
1. Check pint 1 (page 806)
2. A uniform magnetic field B, with magnitude B = 1.2 × 10−3
𝑇, points
vertically upward throughout the volume of a laboratory chamber. A
proton with a velocity 𝑣 = 3.2 × 107
𝑚/𝑠 enters the laboratory moving
horizontally from south to north. Find:
(a) the magnitude
(b) the direction of the magnetic force on the proton.

7. Magnetic Force on Current-Carrying Wire/Conductor
The magnetic field set up by a current-carrying conductor
can
be found from the Biot–Savart law. This law asserts that
the contribution 𝑑𝐵 to the field produced by a current-
length element 𝑖. 𝑑𝑠 at a point P located a distance r from
the current element is

8. Magnetic Field Due to a Current in a Long Straight Wire

9. Magnetic Force on Current-Carrying Wire/Conductor

10. Magnetic Field Due to a Current in a Circular Arc of Wire

11. Force Between Two Parallel Currents

12. Ampere’s Law
The magnetic field in space around an
electric current is proportional to the
electric current which serves as its source.
Ampere's Law states that for any closed
loop path, the sum of the length elements
times the magnetic field in the direction of
the length element is equal to the
permeability times the electric current
enclosed in the loop.
𝐵. ∆𝑙 = 𝜇0𝐼𝑒𝑛𝑐

13. Ampere’s Law
The magnetic field doesn’t vary at a
distance r due to symmetry. The path
length equal to the circumference of a
circle, 2πr. So :
𝐵 =
𝜇0𝐼𝑒𝑛𝑐
2𝜋𝑟

14. Magnetic Field of a Solenoid and Toroid

15. A 200-turn solenoid having a length of 25 cm and a diameter
of 10 cm carries a current of 0.29 A. Calculate the magnitude of the
magnetic field inside the solenoid.
Question

16. Terima Kasih!