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1. Chapter 4. Magnetic field
Western International
School
Department: Physics
Teacher. CHEY Sopheak
Lesson1: The magnetic field due to a
straight and solenoid current-carrying
wire

2. Contents
Magnetic field due to straight line
Magnetic field line in Solenoid
3
1
2
Introduction
Right-hand grip rule for Solenoid
4
Electromagnets
5
Application of Electromagnets
6
A door bell
7
Summary
8

3. Magnetic field due to Solenoid
 What is the formula of magnetic field inside Solenoid?
Magnetic field in solenoid is defined as
Where, B is magnetic filed measured in Tesla (T).
N is the numbers of turns.
is the electric current measured in Ampere (A)
is the length of Solenoid measured in (m).
is the vacuum permittivity.
 Example1: Calculate the magnetic field of an air-core
solenoid containing 320 turn if the length of the solenoid
22.0cm with current 10A across it?
Answer1: Calculate the magnetic field
Using formula:
Hence

4. Right-hand side rule for Solenoid
 What is the symbol specify current and magnetic field
go into plane and out of plane of paper?
 How to find the direction of B & I go into and out of
plane of paper?
Symbol  specify the direction of current and magnetic
field go out of plane of paper.
Symbol  specify the direction of current and magnetic
field go into plane of paper.
Answer:
 Grip the wire with your right fingers
 Pointing your thumb in the direction of the current.
 Your fingers curl around in the direction of the magnetic
field.

5. Right-hand side rule for Solenoid

6. Homework#2
 Assign homework#2 for students after finishing second
session.