Physics 7.3.2 Flashcards
The Generator Effect can be Used to: (2)
-Generate A.C in an Alternator.
-Generate D.C in a Dynamo.
What is an ‘Alternator’?
An Alternator is a Type of Generator that Converts Mechanical Energy to Electrical Energy, in the Form of Alternating Current (A.C).
What is a ‘Dynamo’?
A Dynamo is a Direct Current (D.C) Generator.
What is the Difference in a Dynamo from an Alternator?
A Dynamo has a Split-Ring Commutator, Instead of 2 Separate Slip Rings.
What is a ‘Bicycle Dynamo’, & what does it Consist of?
A Bicycle Dynamo is Used to Supply Electricity to Bicycle Lights whilst in Motion. It Consists of a Rotating Magnet Placed Inside (or next to) a Coil.
Explain how an Alternator Works: (7)
-Generator Effect: When a Coil of Wire Cuts Through Magnetic Field Lines of 2 Big Magnets (1 NP & 1 SP), a Potential Difference is Induced in the Coil. But if the Coil is part of a Complete Circuit, an Electrical Current is Supplied to it Instead.
-In an Alternator, the Coil is Connected to 2 Slip Rings.
-When the Coil is Parallel to the MFL, the Current Flowing Through it is Perpendicular to the MFL, so it Cuts Through them, so a Current is Supplied to it.
-This Causes it to Spin Clockwise, at a Steady Rate of Rotation.
-When the Coil Spins to be Perpendicular to the MFL, The Current Flowing Through it is Parallel to the MFL, so it is not Actually Cutting Through the MFL in this Position, so no Current is Supplied to the Coil.
-Then, when the Coil Spins to be Parallel to the MFL again, but this time Upside Down to the previous time, the Current Flowing Through it is again Perpendicular to the MFL, so Cuts Through them, so a Current is again Supplied to it. But since it is now Upside Down, the Current Supplied to it is in the Opposite Direction.
-So Since the Current Alternates in Both Directions, while the Coil Rotates, it is Defined as Alternating Current.
Explain how a Dynamo Works: (6)
-Generator Effect: When a Coil of Wire Cuts Through Magnetic Field Lines of 2 Big Magnets (1 NP & 1 SP), a Potential Difference is Induced in the Coil. But if the Coil is part of a Complete Circuit, an Electrical Current is Supplied to it Instead.
-In a Dynamo, the Coil is Connected to 1 Split Ring Commutator.
-When the Coil is Parallel to the MFL, the Current Flowing Through it is Perpendicular to the MFL, so it Cuts Through them. This Supplies the Coil with a Current.
-This Causes the Coil to Start Spinning in the Same Direction.
-When the Coil Spins to be Positioned Perpendicular to the MFL, the Current Flowing Through it is Parallel to the MFL, so it isn’t Actually Cutting Through the MFL, so a Current is not Supplied to it in this Position.
-When the Coil Continues to Spin, & it Spins Back to be Parallel with the MFL, the Current Flowing Through it is Perpendicular to the MFL again, so it Cuts Through them Again, Supplying them with a Current. Now it is Upside Down to how it was at the Start.
-But Because a Split Ring Commutator is Used here Instead of Slip Rings, the fact that the Coil is Upside Down is Negated by how the opposite Ends of the Coil are Connected to the Opposite Ends of the Split Ring Commutator than they were in Contact with at the Start. Hence, the Current Flows in the Same Direction as at the Start. Therefore, it is Direct Current (D.C.).
At the Start, Coil is Upright, & SRC is Upright. Coil End A is Connected to SRC Panel B. Coil End B is Connected to SRC Panel A. So Current Flows in Forward Direction.
Once Coil Rotates, it is Now Upside Down (Compared to the Start). So Coil End A is Connected to SRC Panel A, but Because Coil is Upside Down, Current Produced is the Same as at the Start. Coil End B is Connected to SRC Panel B, but Because Coil is Upside Down , Current Produced is the Same as at the Start. So Therefore, Current is Still Going in the Forwards Direction, so it is DC.
(Coil Being Upside Down Negates the fact that Coil Ends are connected to opposite SRC Panels after it flips upside down)
