[Music] candidates are expected to have a thorough understanding of the syllabus details outlined in the accompanying figure the DC motor without the split ring commutator it is the device which changes electrical energy to kinetic energy the simple DC motor consists of a coil of wire which is free to rotate positioned in a uniform magnetic field when the current is flowing in the coil at right angle to the permanent magnetics field the current creates a magnetic field around the coil that interacts with the field from the permanent magnets this produces the forces being exerted on the coil causing it to turn the direction of the force can be determined using Fleming's left hand rule as current will flow in opposite directions on each side of the coil the force produced from the magnetic field will push one side of the coil up and the other side of the coil down this will cause the coil to rotate and it will continue to rotate until it is in the vertical position in the vertical position the magnetic forces on each side of the coil act upward and downward canceling each other out resulting in no net turning effect however the momentum or inertia of the coil keeps it turning until the magnetic force takes the moment of force in the opposite direction again this causes the coil to oscillate with a small angle to prevent this and ensure continuous rotation in One Direction a split ring commutator is used this device reverses the current flow in the coil as it reaches the vertical position effectively changing the direction of the magnetic forces and pushing the coil to continue rotating the DC motor with the split Rings commutator this is the split ring commutator it swaps the contacts of the coil this is the carbon brushes which make sliding contact with the split ring as the coil rotates the carbon brushes are at rest when the current flows through the split ring and coil the force on the blue side is upward due to Fleming left hand rule and the force on the red side is downward as the coil rotates until it reaches a vertical position the Gap in the split ring aligns with the carbon brushes this makes no current flows through the coil causing no forces act on the both sides the momentum of the coil keeps it turning until the blue split ring connects to the red carbon brush and the red split ring connects to the blue brush this reverses the direction in which the current is flowing in both sides of the coil this keeps the current leaving the motor in the same direction reversing the direction of the current will also reverse the direction in which the forces are acting in both sides of the coil as a result the coil will continue to rotate in same direction so the split ring commutator reverses the direction of the current in the coil every half turn when it is vertical this will keep the coil rotating continuously in same direction as long as the current is Flowing the speed at which the coil rotates can be increased by increasing the current use a stronger magnet this causes the magnetic field strength to increase increasing the number of turns in the coil the direction of rotation of coil in the DC motor can be changed by reversing the direction of the current reversing the direction of the magnet magnetic field by reversing the poles of the magnet I hope you found this video helpful if you did I would be grateful if you would subscribe share like and leave a positive comment your support will encourage me to create more content thank you