The source of magnetic field is electric current. In this concept we will discuss about magnetic field due to circular loop. As we know that if current passing through a straight wire then magnetic field creates around it. The magnitude of that magnetic field is inversely proportional to distance from the conducting wire.Now we bend that straight electrical wire and form a circular loop. Are magnetic field lines same as before?
Consider a circular conducting ring. Pass the current through it in anticlockwise direction
Due to current passing through the loop magnetic field lines are produced around that loop. The nature of magnetic field lines are as shown in figure.
The nature of magnetic field due to circular loop:
- When we move towards the centre, the magnetic field lines are straight.
- If we move towards the loop from the centre of loop the Magnetic field Lines are bending towards the loop.
- The direction of magnetic field lines are given by right hand thumb rule.
- If current flow anticlockwise in circuit then the direction of filed lines are upwards.
If current flow clockwise in circuit then the direction of filed lines are downward.
Always remember that the magnetic filed lines and current carrying loop lies in different planes.
- Magnetic field is strongest at the centre. If we travel upward or downward from the loop as indicated above diagram then value of magnetic field decrease.
- The magnetic field lines of circular loop are same for bar magnet.Circular current carrying loop act as bar magnetic.
Consider a carrying circular loop in which current will pass in anticlockwise direction as shown in figure below.
The magnetic field at a point A is
B = (μ₀ I R²) / 2 (x² +R² ) 3/2
Where,
B- magnetic field.
μ₀- absolute permeability.
R- radius of circular loop.
X- distance from the loop.
I – Current flowing through the loop.
- Magnitude of magnetic field is depend on
- Magnitude of current flowing through the loop- If current increases then the value of magnetic field also increases.
- Number of turns wound on circular loop- If we increase number of turns then magnetic field also increase.
- Radius of magnetic field- Magnitude of magnetic field varies to square of radius of loop.
- Distance from loop- Magnetic field also inversely varies with distance from the loop.
Q. The direction of magnetic field is towards the point A from loop and it is determined by right hand thumb rule.
Q) If a current flowing from South to north then what is the direction of magnetic field.
Q) Current carrying loop is placed on plane of south and north. What is the direction of magnetic field when someone see it from east. Current flow anticlockwise direction according to observer.
Q) What will be the source of magnetic field?
Q) What is the relationship between magnetic field due to circular loop and radius of circular loop?
Q) What will be magnetic field at a centre of circular loop?