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Voltage and Current

Bio Med Tech course 1

QuestionAnswer
What parts does an atom consists of? Electrons, Nucleus
What is electrostatic force? When the nucleus and the electron are attracted to each other.
Why is electrostatic force important? Without it the electrons would fly out of orbit.
What charge does electrons have? They have a negative charge.
What is the nucleus made up of? Particles called Protons and Neutrons.
What charge does protons have? They have a positive charge.
What does the positive charge of the proton do to the nucleus? It gives the nucleus a positive charge.
When the number of protons equals the number of electrons, the atom is? Electrically neutral
Law of electrostatics states? Unlike charges attract. Like charges repel
When electrons and protons are balanced what does this do. It keeps the atom electrically neutral.
What happens with an atom that has three electrons and four protons? The atom will GAIN another electron.
An atom with three electrons and four protons is? Electrically charged
Atoms with more protons than electrons are? Positive ions
An atom with four electrons and three protons will? LOSE an electron
Atoms with more electrons than protons are? Negative ions
When there are several negative ions grouped in one area and several positive ions are grouped in another area what is this called? Potential difference
What is the force created by the ions trying to become neutral? Electromotive Force (EMF) or Voltage
When an atom is electrically neutral what happens? There is no potential differnce or voltage
How does an atom to become positively ionized? Orbiting electrons must be forced away from the atom.
What are the six ways electrons are forced to leave an atom's orbit? 1. Friction 2. Pressure 3. Heat 4. Light 5. Magnetism 6. Chemical Action
What is friction? Rubbing one material against another. Only small amounts of voltage can be produced.
What is pressure? Squeezing of certain types of crystals. Produces very small voltages. Most common in microphones and phonograph pickups.
What is heat? Heating between a copper rod and iron rod. Produces small voltages. Used for temperature detecting devices.
How does light produces voltage? By striking light sensitive material such as silver or copper oxide. Produces small voltages. Used in sensing devices such as alarms.
How does magnetism produce voltage? When a metal rod is moved through a magnetic field. Produces large amounts of voltage. Power stations produce electricity using magnetism.
What is Chemical Action? Placing zinc and copper rods in hydrochloric acid produces electricity in a battery.
What is the most common battery? A dry cell. Also called primary cells, which means that the chemicals are used up after awhile, and must be replaced.
Storage cells can be? Recharged. Ni-Cad (nickel-cadmium) and NIMH (nickel-metal hydride) are examples of storage cells.
What is another common battery? The lead acid cell. Better know as a car battery. Also is a storage cell
Who created the first battery? An Italian Physicist, Alessandro Volta
What method of producing voltage is being used to turn on lights? Magnetism
What does a solar powered calculator use to produce voltage? Light
Voltage and what are basically the same? Potential difference. Voltage describes the amount of potential difference present.
Current is what? The movement or flow of electrons.
Electric current developes when? Electrons move from a negatively charged body to a positively charged body
What is equal to 1 Ampere? 6.25 billion billion electrons passing a given poin in 1 second.
Ampere is the measurement of what? The ampere is the basic unit of electric current.
What is current? Current is a continuous flow of electrons.
Electron flow is from what to what? Negative charge to positive charge.
What causes Current to flow? Voltage
Current must have a what to flow? Current must have a path to flow.
What is the path that allows current to flow called? Conductor. A good conductor is made from a material that allows electrons to move freely. Silver, Copper, Gold, Steel
Major factors affecting conductors are? 1. Specific resistivity of the conductor. 2. Lengh of the conductor. 3. Cross-sectional area of the conductor.
Minor factor affecting conductors is? Temperature coefficient.
Specific resistivity of a conductor? Silver 100%. Copper 94%. Gold 61%. Aluminum 55%
What is most commonly used material for a conuctor due to its low cost and read availability? Copper
Longer length conductors offer what? More resistance to electron flow than shorter conductors.
What cross sections provide less resistance to electron flow than smaller conductors? Large cross sections.
All conductors are affected by what? Ambient temperature
When the temperature of a conductor goes up? Resistance to electron flow goes up
When the temperautre of a conductor reduces? Resistance to electron flow will go down
Insulators do what? Prevent electrons from moving
Materials that make very good insulators are? Glass, Paper, Rubber, Plastic
What is electronics? The science of manipulating voltage and current for the purpose of controlling devices.
Voltage is? The force that moves electrons also referred to as Potential Difference
The electric circuit is a device that is? Used to control voltage and current for the purpose of doing useful work.
A simple electric ciruit has what three requirements? 1. Voltage source. 2. Conductor. 3. Load
The voltage source is represented by? The letter (E) or (V)
Current is represented by? The letter (I)
The simple circuit needs a --- that allows charge flows through the device? Load
Load for a ciruit is a? Light bulb
A load provides ----to current? Resistance. (R)
What type of voltage source is the battery? Chemical action termed electrolyte
What keeps an electron in orbit around the nucleus? Electrostatic force and the electrons spinning
What causes the nucleus of an atom to be positively charged? Protons
What are the two basic parts of an atom? The nucleus and the electron
The composition of a negative ion will have? More electrons than protons
How is voltage produced when sunlight strikes silver oxide? Light
A good insulator is made of Rubber
A conductor? Provides a path for current flow
A good conductor is made of Copper
What controls voltage and current for the purpose of doing useful work? Electric circuits
What symbol is used to represent a voltage source? E
Materials that conduct electricity in one direction or only under specific conditions are termed? Semiconductors. Silicon, Germanium
What is electrical potential difference? The ability of an electrial charge to move from one place to another
What is Capacitance? The ability of an object to take charge.
What three components does a complete circuit need to operate? The Condutor- Wire, Solder runs A Load- Light bulb, Resistor, Heating element A Source of electricity- Battery, Power Supply, Power from the wall
What is the term for the flow of electrons? Current flow
What is the difference between a battery and a capacitor? A battery is able to release a charge slowly over a longer period of time.
What is the electricity produced as a result of a chemical reaction called? This chemical is termed electrolyte
Batteries are rated in? Volts
What is the most common type of battery? The Dry cell classified as a primary cell. Alkaline and Lithium
What happens with primary cells? The chemicals will be used up over a period of time and the dead cell must be replaced.
Secondary cells can be? Recharged. Ni-Cad (nickel-cadmium) Ni-MH (nickel-metal hydride) Lead Acid (Car Battery)
What is Power? The amount of energy expended by any electrical device over a given period of time.
How is power measured? Watt
Federal standards for wiring homes and businesses can be found in the ? The National Electrical Code (NEC)
What is Potential Difference? The electrical difference between two points
Potential difference is measured in? Volts
What is often used to represent DC in a direct current source? "V"
What is commonly used to represent alternating current? "AC"
You can do it!! Yeah Lawrence
Created by: 100000215936034