Electric Dipole in a Magnetic Field and the Dipole Radiation

We know a dipole is a pair of opposite charges that are separated by a distance. This article will give you the details on the force acting on a dipole in a uniform magnetic field known as torque. Torque is the force that makes the object rotate about an axis. It is a vector quantity, and its direction depends on the direction of the force on the axis. You may know that magnetic dipoles are used in magnetic compass needles and bar magnets in real life. We will also learn what happens to a dipole in a uniform magnetic field? Or, What is an oscillating electric dipole? 

Torque Acting on a Dipole in a Uniform Magnetic Field

Let quantity yz be the area of loop A from which the electric current passes. The loop will act as the electric dipole when the current passes through it. Current is fed into the loop by a single wire, which is wound around the perimeter several times. 

The force will be exerted on each side of the loop by the magnetic field. This force is called torque and it is given by multiplying by the number of turns in the wire N, current I, and area A. The product of all these three values is written as a single quantity μ, giving the magnitude of the torque of the dipole in a uniform magnetic field as  

τ=μB, in a simple form. 

The moment of the arm will shrink if the loop turns upon its axis. 

For example, when the top segment of the loop rotates back and the bottom rotates front by 900, then the forces on those segments will be directed away from each other. The forces will be acting straight on the axis and therefore the torque will be zero. 

Torque and magnetic fields are the quantities that have direction and therefore they are vector quantities. The torque created by them is related to the position of the loop in the magnetic field. We can account for the loop position by defining a magnetic dipole moment:

μ≡NIA

Here, A is the vector that has an equal magnitude to the area of the loop and is in the direction which is perpendicular to the plane of the loop.

The right hand’s direction can be given by the right-hand rule: Curl the fingers of your right hand in a direction that gives the direction of the current around the loop, and the thumb of that hand points the direction of the vector. 

What is Dipole Radiation?

Dipole radiation can be defined as an extension, or an advance next step physically in spherical wave radiation. In specific terms, it is taken as a harmonically oscillating electric dipole, having an angular frequency ω and a dipole moment p0 along the ẑ direction of the form. Thus, now you may have got the answer: What is an oscillating electric dipole? 

Radiation power of an oscillating electric dipole (Dipole Radiation)

The radiation given out by electric dipole (short) doing oscillation is written as,