What is a Solenoid
It is a coil containing many circular turns
These wires are wrapped closely in the shape of a cylinder.
It looks like
If we pass current through the circuit, the magnetic field would be shown as
Let's look at some properties of Magnetic Field produced in Solenoid
Solenoid behaves like a bar magnet
A solenoid behaves like a bar magnet when current is passed through it.
Like in bar magnet, the field lines emerge from one end and merge into another.
In a solenoid, the field lines behave in the same manner
One end of Solenoid behaves as Magnetic North Pole
and Other end as Magnetic South Pole
Field lines are parallel straight lines inside solenoid
It means magnetic field is same at all points inside the solenoid,
that is, magnetic field is uniform inside a solenoid.
Magnetic Field Produced is Strong in a Solenoid
A solenoid has a number of turns
More the number of turns, more the current flows through it and hence more the magnetic field
Hence, they are used to make electromagnets
Strength of Magnetic field in a Solenoid depends on
Strength of Magnetic field in a Solenoid depends on
- Number of turns in the solenoid - More number of turns, greater the magnetic field
- Strength of current in the solenoid - More current, more the magnetic field
- Nature of Core Material used inside the solenoid - If we use soft iron inside the solenoid, it produces the strongest magnetism
What is an Electromagnet
An electromagnet is a magnet consisting of wire would around a soft iron core.
It is magnetized only when electric current is passed through the coil.
Example
A soft piece of iron is placed inside solenoid
When electric current is passed, strong magnetic field is created.
The iron becomes magnetic due to the strong magnetic field of the solenoid.
The magnet so produced is called electromagnet
Note : Only soft iron is used to make an electromagnet because Core of an Electromagnet loses all its magnetism when current is switched off.
That is why steel is not used to make electromagnets - It doesn't lose all its magnetism when current is switched off
Questions
NCERT Questions 8 - How does a solenoid behave like a magnet? Can you determine the north and south poles of a current–carrying solenoid with the help of a bar magnet? Explain.
Question 2 Page 229 - The magnetic field in a given region is uniform. Draw a diagram to represent it.
