Unit C | Topic 3.1-3.3 | Motors and energy Flashcards
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Definition of:
Energy
The ability to do work
Definition of:
Chemical energy
The energy found in chemical bonds (considered potential energy)
Definition of:
Thermal energy
Is the total kinetic energy of all moving particles in a substance (basically the heat electrons produce because of friction)
Definition of:
Electrical energy
The energy of charged particles
Definition of:
Mechanical energy
The energy of an object because of its motion (or potential to move)
What is the first law of thermodynamics?
Energy can’t be created or destroyed, only transferred
Definition of:
Thermocouple
A device that converts thermal energy into electrical energy
How does a thermocouple work?
When the metals are heated, the difference in conduction results in electricity flowing from one metal to the other
Who invented the first electric motor?
Faraday
How does an electromagnet work?
When electricity flows through a circuit, it aligns the elections in one direction like a magnet, creating a magnetic field.
What are the tree components of an electromagnet?
- Power source
- Coil of wire
- Metal core
What are three ways to increase the strength of an electromagnet?
- Increase the size of the core
- Increase the strength of the current (+V)
- Increase the # of coils around the the core
What happens if the current is reversed in an electromagnet?
Magnetic field inverts
(North and South switch)
Definition of:
Electric motor
A device that converts electrical energy into mechanical energy
What components does an electric motor require?
- An armature
- A permanent magnet
- Brushes
- A commutator
Definition of:
Commutator
A split ring that breaks the current for a moment then reverses the current to maintain rotation
Definition of:
Brushes
Electrical contacts with the commutator that permit electrons to flow through the armature
Definition of:
Permanent magnet
Creates a magnetic field with north and south poles, which interacts the the armature and causes it to spin
Definition of:
Armature
A rotating shaft with a coil wrapped around it
Definition of:
Alternating current
Current that flows back and forth 60 times a second
Definition of:
Direct current
Current that only travels in one direction
Who invented alternating current?
Nicola Tesla
Who invented direct current?
Thomas Edison
Definition of:
Transformer
A device that changes electricity from one voltage to another one
Definition of:
Electromagnetic induction
Electrical current generated by moving a conductor through a magnetic field
Definition of:
Generator
A device that converts mechanical energy into electrical energy
What is the formula for Power?
P = I x V
Power = Current x Voltage
or
P = E / T
Power = Energy (joules) / Time (seconds)
What is the formula for Cost of electricity?
Cost = Energy consumed (kW/hr) x $ charged per kW/hr
What is the formula for effeciency?
Efficiency (%) = [Useful energy output / Total energy input] x 100
What components are on an energuide manual?
- Annual energy consumption of the appliance in kW/hr
- The energy consumption indicator - compares the model to others in it’s class
- Energy consumption of the most and least efficient appliances in its class
- The type and capacity range of similar models compared
What are two major ways to increase the energy efficiency of a device?
- Decrease friction (using bearings and lubricants)
- Adding more insulation to reduce heat loss
