Physics 7.2.4 Flashcards
What can the ‘Motor Effect’ be Used to Create? What does it Consist of?
A Simple D.C. Electric Motor. Consists of a Coil Wire (which is free to Rotate) Positioned in a Uniform Magnetic Field.
What does a ‘Split Ring Commutator’ do’?
Swaps the Contacts of the Coil. This Reverses the Direction in which the Current is Flowing.
The Speed at which the Coil Rotates can be Increased by: (2)
-Increasing the Current.
-Use a Stronger Magnet.
The Direction of Rotation of Coil in the D.C. Motor can be Changed by: (2)
-Reversing the Direction of the Current.
-Reversing the Direction of the Magnetic Field by Reversing the Poles of the Magnet.
The Force Supplied by the D.C. Motor can be Increased by: (3)
-Increasing the Current in the Coil.
-Increasing the Strength of the Magnetic Field.
-Adding More Turns to the Coil.
Explain how the Motor Effect is Used to Create an Electric (D.C.) Motor: (5)
-Current is Supplied to Armature. This Creates MFL around it. Like a Flat Bar Magnet. Top half is NP, Bottom half is SP.
-Placed in between 2 Big Magnets, 1NP & 1 SP. Armature is Placed so that the Current Flowing through it is Perpendicular to the MFL of the Big Magnets.
-Due to the Motor Effect, a Force Acts on the Armature. This Causes it to Spin, Such that its NP Spins towards the Big SP, & its SP Spins Towards the Big NP.
-To keep it Constantly Spinning like this, a Split Ring Commutator is Added. The SRC is Added to the Armature via 2 Contact Brushes. When the Armature Spins, the Contact Brushes Slide Onto Opposite Panels on the SRC. This Simulates Manually Switching the Wires of the Armature; The Current Flowing through the Armature Changes Direction. When the Current Changes Direction, the Armature’s MFL also Flip Directions, so its NP becomes it SP, & its SP becomes its NP. This keeps it Constantly Spinning.
-An Axel is Added to the Other End of the Armature. Now, it is an Electric (D.C.) Motor.
