Composition of Matter/Current, Voltage & Resistance Flashcards
What is a conductor?
A material having 1 to 3 valence electrons that will easily become free electrons to transmit electricity. (materials with low resistance)
What is an insulator?
A material having five or more valence electrons that prevents the normal transmission of electricity. (materials with high resistance)
What is a semiconductor?
A material having four electrons in the valence band of its atoms and is neither a good conductor or good insulator.
What is a neutron?
A particle in the nucleus of an atom that has no electrical charge. However its mass is approximately the same as a proton.
What is an electron?
A particle rotating in orbit around the nucleus of an atom. It has a negative electrical charge.
What is a compound?
A substance made by combining elements
What is an ion?
An atom that has gained or lost an electron
What is a valence electron?
An electron in the valence shell of an atom that is loosely bound to the atom and may readily leave its orbit.
What is a free electron?
An electron that is dislodged from its atom
What is matter?
Anything that has mass and occupies space
What is cohesion?
A force that binds molecules together
What is solid?
Having hardness and rigidity (length, thickness and breadth)
What are elements?
The basic material that goes into the make up of all matter
What is mass?
The bulk or size of matter
What is energy?
The capacity for doing work. Heat or electricity are examples
What is a nucleus?
The center core of an atom
What is a valence shell?
The outermost orbit in which electrons may revolve around the nucleus of an atom
What is a proton?
The positively charged particle in the nucleus of an atom
What is resistance?
The property of a material that opposes the flow of an electric current in a circuit
What is a molecule?
The smallest particle into which a compound may be divided and still keep its original identity. (The smallest particle you can have that still maintains the same traits)
What is an atom?
The smallest particle of an element that still retains all the properties of the element
What is voltage?
Voltage is in the imbalance of electron distribution (or charges), or a difference in charge between two points.
What are the six methods of producing EMF?
Magnetic, chemical, friction, heat, pressure and light
Conventional current flow can also be referred to as ___ ___.
Hole flow.
What is conventional current flow?
It describes the movement of charge through a conductor from the positive source to the negative source.
What is electron flow?
It describes the movement of charge through a conductor from the negative source to the positive source.
What is static electricity?
The build up of charge in an insulated object.
An electric field and free electrons make up a what?
An electric current.
When is an electric field or force established?
It is established between two sources of charge that are separated, one positive and another negative.
What is electromotive force?
The force that maintains the difference in charge
What is the abbreviation for electromotive force?
EMF
The symbol for EMF is what?
E
What is the unit of measurement for EMF?
Volt, represented by the letter V.
What is an electric circuit?
The connection of a source of emf to both ends of a conductor
What are the three components a practical electrical circuit consists of?
Source of EMF, conductors and load
What is the symbol used for the concept of resistance?
R
What is resistance measured in along with its symbol?
Ohms, Ω
Describe Ohm’s law
The current in a circuit is directly proportional to the EMF applied to the circuit and inversely proportional to the resistance of the circuit.
What letter is used to represent electric current?
I
What is used to measure electric current?
The unit of measurement for current is an ampere.
Amps, A
What is the symbol used to represent quantity of charge?
Q
What is quantity of charge measured in?
Coulombs, C
What is an electric current?
An electric current is the flow of electrons from a negatively charged point to a positively charged point.
What are the two basic components in the universe?
Matter and energy
Matter exists and what four physical states?
- solid
- liquid
- gas
- plasma
Energy and matter cannot be created or destroyed; however, matter can be changed into energy and energy into matter.
True or False
True
When matter has low energy or is under pressure it is said to be in what state?
Solid
The northern lights is an example of what?
A cool plasma
A lightning bolt is an example of what?
A hot plasma
Plasma is an ionized gas,
True or False
True
The two main properties of matter are what?
Chemical and physical
Substances composed of only one type of atom are called what?
Elements
Substances composed of more than one type of atom are called what?
Compounds
What is required to change matter from one state to another?
Energy
How can the physical properties of matter be identified?
Sight, smell, taste, touch or hearing
What are the particles rotating around the nucleus of an atom?
Electrons
What 2 particles are found within the nucleus of an atom?
Protons and neutrons
Neutrons have the same size and mass as a proton but differ in charge.
True or False
True
The atomic number of an element refers to what?
The number of electrons found in the orbiting paths around the nucleus equals the number of protons in the nucleus (in a neutral state).
What is the law of electrical charges?
Unlike charges attract each other, while like charges repel each other.
Since protons repel each other they do not stay within the nucleus of an atom.
True or False
False, although there is a repelling force between the protons in the nucleus, it is counteracted by an atomic binding force within the nucleus.
What is the atomic number for copper and how many electrons are in its valence shell?
29, 1.
What is a positive ion?
When an atom has lost electrons.
What is the negative ion?
An atom that has gained electrons.
If a positively charged particle and a negatively charged particle are close together the force developed between them is one of ___.
Attraction
An element is the smallest particle into which a compound can be divided and still keep its original properties.
True or False
False, not an element but a molecule
Atoms that have the same number of electrons and protons are considered to be what?
Neutral
What is the symbol that is used to represent electrical charge?
Q
Potential difference may be described as a difference in electron distribution between two points of an electric circuit.
True or False
True
When a potential difference exists across an open portion of the circuit a current will flow.
True or False
False, current will not flow
A thermocouple is one method of producing and electromotive force.
True or False
True
A coulomb is a measure of:
Current
Amperes
Charge or
Voltage
Charge
Ohm’s law, written in the form of an equation, would be what?
I=E/R or E=IR or R=E/I
A generator is a device that uses the magnetic principle to produce electricity.
True or False
True
The equation that shows the relationship between coulombs and current would be:
I=Q/t or Q=It or t=Q/I
The name used to describe the current that flows from positive to negative in the external circuit is:
Conventional
The unit of measurement for resistance is the:
Volt
Ampere
Ohm or
Coulomb
Ohm
A coulomb is the measure of a certain number of what?
Electrons
The symbol used to represent the source voltage of an electric circuit is what?
E
The flow of electrons from one point to another is caused by:
a) Magnetic attraction
b) Repulsion of protons from a negative terminal
c) A difference in charge between two points
c, A difference in charge between two points
The type of electricity produced by the rubbing together of two materials is called:
frictional, conventional, static, electron flow or none of the above
Static
What is an example of static electricity?
shoes rubbing against a rug
The symbol used to represent a volt drop within an electric circuit is what?
V
The unit of measurement for an electric charge is what?
Coulomb
And electric field is a force that exist between ____ charges.
different
The circuit property that opposes the flow of current within a circuit is called what?
Resistance
To have an electric current, you must have an electric field and free electrons.
True or False
True
A coulomb represents approximately 6.28 x 10¹⁸ of electrons.
True or False
True
How is voltage measured between two different points?
Voltage is measured across a device, between two conductors or between two separate points along the same conductor.
What is current?
The flow of electrons in a conductor that joins the source of negative charge to positive charge and is measured in amperes (A).
One volt is the value of the difference in charge that will cause a current of one ampere to flow in a circuit with a resistance of one ohm
True or False
True
Which electrons are active in the electron flow?
Free electrons
The direction of electron flow is determined by what?
The polarity of the source