The electromagnetic force is a fundamental interaction between charged particles, encompassing both electric attraction and repulsion as well as magnetic interactions, governed by Maxwell’s equations and quantified through the concept of electromagnetic fields.
When a positively charged balloon is brought close to a negatively charged balloon, they are pulled towards each other due to the electromagnetic force.
A compass needle aligns with the Earth’s magnetic field, demonstrating the magnetic interaction arising from the electromagnetic force.
A magnetic field produced by a current-carrying conductor is a region of influence around the conductor where moving electric charges generate a circular pattern of magnetic lines of force perpendicular to the direction of current flow. This magnetic field can induce magnetic interactions with nearby objects and other currents.
Now suppose a particle carrying charge q is projected with speed v into a magnetic field of magnetic induction B such that the angle between B and V is θ. The magnetic field of the charged particle interacts with the magnetic field of the magnet in which it is sent, due to which a force is produced which acts upon the particle. It is found that:
Combining the above three observations, we found that:
F=q VxB
So the magnitude of B is given by:
\[ B = \frac{F}{qv\sin\theta} = \frac{\text{Newton}}{\text{Coulomb} \cdot \text{meter/second}} = 1 \text{ Tesla}. \]
A magnetic field is a region of space where magnetic forces are exerted on charged particles in motion, arising from the movement of electric charges.
The magnetic field around a bar magnet influences nearby iron filings, causing them to align along the field lines.
Magnetic field lines are visual representations used to depict the direction and strength of magnetic fields, forming closed loops that indicate the path a compass needle would take.
The field lines around a current-carrying wire form concentric circles, illustrating the magnetic influence of the wire’s current.
When a current-carrying conductor is placed in a magnetic field, a force is exerted on the conductor perpendicular to both the current direction and the magnetic field direction.
The force (F) on a current (I) carrying conductor of length (L) in a magnetic field (B) is given by the formula:
F = I (L x B)
F = BIL Sinθ
\begin{equation} B = \frac{F}{\left(\frac{I}{\sin\theta}\right)} \end{equation}
The turning effect of a current-carrying coil in a magnetic field, also known as the magnetic torque, refers to the rotational force experienced by the coil due to the interaction between its current and the magnetic field.
The magnetic torque (τ) on a current-carrying coil with (N) turns in a magnetic field (B) is given by the formula:
Where,
(I) is the current flowing through the coil,
(A) is the area of the coil,
(θ) is the angle between the normal to the coil’s plane and the direction of the magnetic field.
Consider a rectangle coil placed in the magnetic field of strength B and the plane of the coil is parallel to the field and is free to rotate about an axis.
When current (I) passed through the coil, a force is experienced on the perpendicularly placed conductor. The magnitude of the force is F = BIL. Hence a pair of two equal but opposite forces (couple) acts on the coil. That causes the coil to rotate.
So,
Torque = τ = BIA
If the plane of the coil makes an angle a with the field B then the perpendicular distance Cos (a) can be added:
τ = BxIxAxCosa
If the coil has N turns, then:
τ = BIANCos α
