Unit D Electrical Principles: 3.0 Flashcards
What is the definition of energy?
The ability to do work
What are the 4 common forms of energy?
Chemical Energy
Electrical Energy
Mechanical Energy
Thermal Energy
Explain Chemical energy
- The energy stored in chemicals.
- This is a form of potential or stored energy.
- This energy is released when chemicals react.
Explain electrical energy
- The energy of charged particles.
- Electrons are negatively charged.
- Electrical energy is transferred when electrons travel from place to place.
Explain mechanical energy
- The energy possessed by an object because of its motion or its potential to move.
- A thrown baseball has mechanical energy because of its movement and its potential to fall.
Explain thermal energy
- The total kinetic energy of all the particles in a substance.
- The faster a particle moves, the more kinetic energy it has.
- Compare two cups holding equal amounts of water: the one containing more thermal energy will feel warmer.
What is the type of energy found in food?
Chemical energy
What is a thermocouple?
A device that can convert thermal energy to electrical energy.
How does a thermocouple work?
- 2 different metals that conduct heat at different rates are joined together
- When they are heated the difference in conduction results in electricity flowing from one metal to another
Why are thermocouples useful?
Thermocouples are very useful for measuring temperatures in areas that are difficult to access or that are too hot for a liquid-filled glass thermometer.
How did early scientists make electromagnets?
By winding a current carrying wire into a coil around an iron core and putting electricity through it.
How do electromagnets keep spinning in an electric field?
By switching the direction that the current travels. That way it will align with the north and south fields so it will have to keep turning.
How do electric motors reverse the flow of electricity?
They use commutators and brushes
What is a commutator?
The commutator is a split ring that breaks the flow of electricity for a moment and then reverses the connection of the coil
What is a brush?
The part of an electric motor connected to the split rings and the power source usually made of carbon
What is the armature?
The rotating shaft with coils wrapped around it.
Explain how an electric motor works
Electricity runs through a wire to brushes which are connected to a split ring commutator. The split ring is connected to a coil that is wrapped around an armature. The electricity running through the coil creates an electric field which attracts magnets which cause it to spin to align with the electric fields.
What is direct current?
When electricity runs in only one direction
What is alternating current?
Current that flow back and forth 60 times per a second
What are transformers?
They change the amount of voltage with hardly any energy loss
Why are transformers necessary?
Because power lines carry very high voltage nd it must be transformed down before it reaches houses.
How does a transformer work?
A primary coil, with a lot of electricity flowing through it, is wrapped around an iron core with a secondary coil wrapped around the other side with fewer loops. If the loops are less than the voltage goes down.
What is electromagnetic induction?
When electrical current could be generated by moving a conducting wire through a magnetic field.
What does a generator use to function?
Electromagnetic induction
Explain a how a generator work?
By moving a coil of wire past permanent magnets. As long as it keeps turning electricity will be produced. The faster you turn the more current that will be generated.
What is the difference between a DC generator and an AC generator?
The central axle of an AC generator has a loop of wire that is attached to two slip rings. The slip rings create an alternating current.
What is power?
The rate at which a device converts energy
What is the unit of power?
Watt
What is the formula to find power?
Volts x Current (amps)
What is the unit for energy?
Joules
What is the formula for energy?
Power x time (in seconds)
What is the law of conservation of energy?
Energy cannot be created or destroyed. Energy does not just appear or disappear—it can only be transformed from one form to another.
Why aren’t machines 100% efficient?
Because of friction
What is efficiency?
The efficiency of a device is the ratio of the useful energy that comes out of a device to the total energy that went in
What is the formula for efficiency?
Useful output energy (joules)/ input energy (joules)
