Explanation of Magnetic Effects of Electric Current

The Right-Hand Thumb Rule

The Right-Hand Thumb Rule or Maxwell’s Corkscrew Rule depicts the direction of magnetic field in relation to the direction of electric current through a straight conductor.

As per this rule suppose if a current carrying conductor is held by right hand with the thumbs up straight and the electric current flowing in the direction of the thumb then the direction of the magnetic field can be depicted by the direction of wrapping of the other fingers.

This means that in a vertically suspended current carrying conductor if the direction of the current is from south to north then the magnetic field will be in an anticlockwise direction. But if it is vice-versa which means that the direction of the current is flowing from north to south then the magnetic field will be in clockwise direction. In this rule, it should be noted that when current is flowing in an anticlockwise direction, then the magnetic field will be in a clockwise direction at the top of the loop and when it is vice versa then the magnetic field will be at the bottom of the loop.

Flow of Current Through a Circular Loop

Like in the above observation if the electric current carrying conductor is circular shaped instead of a straight current conductor the magnetic field is generated in the same manner. This is because as the electric current carrying conductor exerts a force when a magnetic needle is placed near it, similarly a magnet also exerts an equal and opposite pressure on the electric carrying conductor. Here it is observed that with the change in direction of the flow of current the force of magnet on the conductor also changes. As mentioned above this is because of the SNOW RULE. In a circular loop, the strength of the magnetic field will be more because in this case, the magnetic field is very close to the current carrying conductor.

Clock Face Rule

Let us assume a current carrying circular loop as a disc magnet. The polarity of this disc magnet can be explained with the help of clock face rule. An anticlockwise flowing current will depict the face of the loop showing towards the North Pole.

Magnetic Field Due To A Solenoid

The coil with many circular turns of insulated copper wire wrapped closely in the shape of a cylinder is called a Solenoid. A solenoid behaves similarly like a magnet, one end of solenoid behaves as the north pole and another end behaves as the south pole. In this case, the magnetic field lines are parallel inside the solenoid, which is similar to a magnet and this proves that that magnetic field is same at all points inside a solenoid. By producing a strong magnetic field inside a solenoid, magnetic materials can be magnetized. Magnets formed by producing a magnetic field inside a solenoid is called electromagnet.

Fleming’s Left-Hand Rule

According to Fleming’s Left-Hand Rule, if the direction of flow of the electric current is perpendicular to the magnetic field, the direction of its force is also perpendicular to it. It states that suppose if the forefinger, thumb, and the middle finger of the left hand is stretched in a way that they are right angles to each other, then the forefinger and middle finger show the direction of magnetic field and direction of electric current respectively and the thumb shows the direction of motion or force acting on the current carrying conductor. The directions of electric current, magnetic field and force are similar to three mutually perpendicular axes, i.e. x, y and z-axes.

Application of Fleming’s Left-Hand Rule in Real Life Concepts

Electric Motor

The electric motor is a phenomenal example of how Fleming’s Left-hand rule works, Electrical energy is converted into mechanical energy by using an electric motor. In an electric motor, a rectangular coil is suspended between the two poles- North and south of a magnetic field. The electric supply to the coil is connected to a commutator- a device which reverses the direction of flow of electric current through a circuit.

When an electric current is supplied to the coil of the electric motor, it gets deflected because of the magnetic field. As it reaches the halfway, the split ring which acts as commutator reverses the direction of flow of electric current. When the direction of current reverses the direction of forces acting on the coil also gets reversed. Thus here the change in direction of force pushes the coil, and it moves another half turn. Finally, the coil completes its one rotation around the axle. Continuation of this process keeps the motor in