Topic 3.0: Devices And Systems Convert Energy Flashcards
Chemical energy
Sugar contains this energy
The cells in our body use glucose (sugar) molecules in a series of chemical reactions to produce thermal and mechanical energy
Electrical energy
Energy of charged particles
Is transferred when negatively charged electrons travel from place to place
Mechanical energy
The energy an object has because of its motion or potential to move
A thrown baseball has mechanical energy because of its movement and its potential to fall
Thermal energy
Total kinetic (energy of motion) of all the particles in a substance The faster a particle moves the more kinetic energy it has
Energy
The ability to do work
Forms: electrical, chemical, mechanical and thermal
Energy transformation
Input energy and output energy
Ex. Toaster- electrical to thermal
Thermocouple
Transforms thermal energy into electrical energy
Made of two different metals that are joined together which conduct hear at different rates
When heated the difference in conduction results in electricity flowing from metal to the other
Practical uses of thermocouples
Car engines- temp in a car can be extreme and the reading may come from deep in the engine
A thermocouple can withstand these high temps because it generates electrical energy that can gauge from the thermocouple sensor for convenient temp readings
Polarity
Refers to the condition of having north or south ends such as in a permanent magnet
Faradays device
He constructed a device that used electromagnetic forces to cause an object to move around a magnet
This eventually led to the development of the electrical motor
He also demonstrated that electrical current is created in a wire that moves a magnet field which lead to the modern electric motors
Generators create electrical current
Electric motors
Reversing the current reveres the polarity of an electromagnet thereby keeping it spinning
Use a commutator, brushes, armature, magnets and coil
Commutator and brushes
Reverse the flow of electricity through the electromagnetic coil
Commutator- split ring that breaks the flow of electricity for a moment and then reversed the connection of the coil
Brushes- bars of carbon pushed against the commutator by springs
They make electrical contact with the moving commutator brushing against it
Armature
Continues to spin because of momentum
It is the rotating shaft with the coil wrapped around it
Magnets
They can be adjusted to alter the speed of the spinning coil by being closer or farther away from the coil
Attractive and repulsive forces make the coil turn
Allowing the commutator to change position so it’s one side touches the brush
Direct and indirect current
DC: current flows in only one direction- positive terminal to negative terminal
Alternating current AC: current flows back and forth, alternates direction
Transforms change the amount of voltage without energy loss
Voltage change is necessary because the most efficient way to transmit current over long distances is at high voltage