Electrical and Mechanical Engineering Flashcards
Electricity/Electrical
- uses conductors (metals & alloys, usually copper) to link different circuit components (motor, heater, light, power source, switch, fuse, etc).
-most often uses AC power and high current (exception: small DC motors). - EX: fan or heater, flashlight
- doesnt think
Electronics
- (also uses conductors to links components)
- uses semiconductors (usually silicon or germanium) to perform complex tasks (control current flow, store information, etc)
- always uses DC power and low current.
- EX: Cell phone, calculator, computer, toy car, ps5, switch, smart watch, radio, printer
- thinks
What is in common with electronics and electricity?
Both electric and electronic circuits use insulators (plastic, rubber, ceramic, glass) to prevent short circuits and protect the user and equipment.
5 electrical conductors
silver, gold, copper, steel, sea water
5 electrical insulators
glass, dry wood, oil, rubber, diamon d
4 Electrical Functions!
Power Supply
Conduction / Insulation / Protection
Control
Transformation of Energy
What is a function
Function is what something does, the job it accomplishes.
Power Supply
Power Supply: provides the “push” (potential difference, or Voltage) that moves electrons in the circuit (see next slide)
Conduction
Conduction: wires (usually copper) connect components of the circuit
Control
(3) Control: performed by a component that can open or close a circuit branch. There are many types of switches (pushbutton, toggle, slider, momentary, etc)
Transformation of Energy
Transformation of Energy: the main “job” of a circuit element.
Components in a circuit can transform electrical energy into many other forms, allowing them to perform a task.
- light bulb - heating element - electromagnet - piezoelectric crystal
Insulation
Insulation: prevents electric current from flowing -rubber/plastic
Protection
Protection: component that automatically cuts current flow when there is a power surge. Protects the circuit, not the human
- fuse - circuit breaker
Fuse
(one time deal, it explodes and burns out instead of the actual thing)
Component of linking
Component: a solid part or fluid that performs a mechanical function (Ex: a metal gear in a clock; the oil in a hydraulic piston)
Linking
Linking: the mechanical function performed by any component that connects different parts of a technical object.
→ A linking component connects parts of an object.
Direct
A link is direct when two parts hold together without a linking component
Indirect
A link is indirect when the parts require a linking component to hold them together.
Rigid
A link is rigid when the linking component or the surfaces of the linked parts are rigid.
Flexible
A link is flexible when the linking component or the surfaces of the linked parts can be deformed. Springs and rubber are often used in flexible links
Removable
A link is removable when the linked parts can be separated without damaging either their surface or the linking component (if present). Nuts and screws, for example are used in removable links.
Non-removable
A link is non-removable when separating the linked parts damages their surface or the linking component.
Complete
A link is complete when it prevents the linked parts from moving independently of one another.
Partial
A link is partial when a least one part can move independently from other parts.
Direct / indirect
Direct / indirect
(Is there something extra needed to hold components together?)
Rigid / flexible
(Can the link be deformed, and does it return to its original state?)
Removable / non-removable
(Will the components or links be damaged if separated?)
Nails are considered non-removable
Screws are considered removable
Complete / Partial
(can the parts move relative to each other?)
Component of guiding
Component: a solid part or fluid that performs a mechanical function (Ex: a door hinge; the track of a sliding window)
Guiding
Guiding: the mechanical function performed by any component that controls the motion of one or more moving parts.
Types of Guiding
Translational, Helicoidal and Rotational
Translational guiding
Translational guiding: moves back and forth along a straight line
Examples: drawers, sliding window
+ SYMBOL
Rotational guiding
Rotational guiding: ensures an object rotates
Examples: scissors, bicycle wheel
SYMBOL
Helicoidal
Helicoidal guiding: rotating a component ensures a translational motion
(helical)
EXAMPLES: Clamp, screw press, faucet, jar cap
SYMBOL
Adhesion
Adhesion is the phenomenon by which two surfaces tend to remain in contact with each other without slipping
Battery vs Outlet power source
Battery (DC, low power) -Outlet (AC, high power) -photovoltaic cell
Friction
Friction is a force that resists the slipping of one moving part over another
Lubrication
Lubrication is the mechanical function performed by any component that reduces friction between two parts.
Types of lubricant
Liquid, semisolid, solid
Liquid lubricant
Water, oil (vegetable, animal and mineral)
Semisolid lubricant
Suet, Vaseline, animal fat, vegetable fat
Solid lubricant
Graphite, paraffin
Motion transmission
Motion Transmission is the mechanical function of relaying a motion from one part to another without changing the nature of the motion.
(rotation → rotation)
2 Types of Dynamic Electricity
AC/DC
AC current
Electrons “wiggle” back and forth. This “wiggling” is caused by the AC power source. The motion is communicated from electron to neighboring electron all along the wire.
Power generating stations produce AC current. AC current is optimal for sending electricity long distances (DC current has too much loss).
DC current
Electrons travel through the conductors from one end to the other, pushed by the potential difference (voltage) of the DC power source (ex: battery).
DC current ex
Most electronic devices function on DC current. The “box” on power adaptors converts the AC current from the wall outlet to DC current for the electronic device.
AC current ex
AC current can power motors, heating elements, and other simple mechanical devices.
Electric current
An electric current is the orderly flow of negative charges carried by electrons
Conventional current
The conventional direction of a current is from the positive terminal of a power supply towards the negative terminal. (This is opposite of Electron Flow.)
(Think back to our electric field drawings from static electricity: FROM positive TO negative!)
