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Voltage and Current
Bio Med Tech course 1
Question | Answer |
---|---|
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 |