Magnetic Field due to a Solenoid Carrying Current :Class X Physics

Mgnetic Effect and Electric

If we wounded a copper in the form of a cylindrical coil having diameter less the length of wire , we get a helical spring called a solenoid. A cylindrical coil of insulated wire having many turns is called solenoid

If current passes through solenoid
1. One end of the coil acts like a magnetic north pole while the other acts like a south pole.The polarity of the solenoid can be changed by reversing the direction of the current.

2. The lines of force inside the solenoid are nearly straight and parallel to the axis of the solenoid.

3. A strong magnetic field can be obtained by increasing the current strength.

4. The magnetic field is increased if the number of turns in the solenoid of given length is increased.

5. The magnetic field is also increased if soft iron core is kept along the axis of the solenoid.

The strength of the magnetic field produced by a current carrying solenoid depends on:
(i) The number of turns in the solenoid : Larger the number of turns in the solenoid, greater will be the
magnetic field produced. 

B µ I
(ii) The strength of current in the solenoid : Larger the current passed through solenoid, stronger will be
the magnetic field produced.

B µ n       [Here, n =N/L or, Number of turns per unit length]
(ii) The strength of current in the solenoid : Larger the current passed through solenoid, stronger will be
the magnetic field
Magnetic field inside the solenoid is :

B µ  In

 B = m_0/2(In)

µ₀ is the permeability constant for free space    

µ0 = 4π × 10^-7 T· m/A.

If we use of soft iron rod as core in a solenoid produced the strongest magnet.till current passes through it. Such magnet is known as electromagnets

A permanent magnet is made from steel alloys like carbon steel, chromium steel, cobalt steel, etc. They are weaker than electromagnets and their strength and polarity cannot be changed.