2: Getting Down To Basics Flashcards
True or False: There are over 100 kinds of atoms.
True
What primarily differentiates atoms, or elements, from each other?
The number of protons and neutrons in their nucleus.
Atoms of elements can join together in groups to form what?
A molecule.
Example: Two atoms of hydrogen and one atom of oxygen form a molecule of water.
What are found outside the nucleus and carry a negative charge?
Electrons.
True or False: The nucleus is positively charged.
True.
Will a neutral atom that gains electrons result in a negative or positive charge?
Negative.
Atoms that gain electrons from a neutral state become negatively charged.
What is electrostatic attraction?
The phenomenon where negative electrons are held in place by the positive protons in the nucleus.
True or false: Particles with like charges attract each other.
False.
Particles with opposite charges attract each other. Like charges repel each other.
What is the name for a charged (negatively or positively) atom or molecule?
An ion.
What is the process of an atom or molecule becoming (negatively or positively) charged called?
Ionization.
What are valence electrons?
The electrons in the outdoor shell of an atom.
These atoms can be put under stress and caused to move to another atom.
What is electrical current?
The flow of electrons.
What is a conductor?
The substance through which current, or the flow of electrons, moves.
What is a coulomb? How is it abbreviated?
The basic unit of charge. 6.28 x 10E18 electrons.
What is an ampere? How is it abbreviated?
The rate of flow of electrons. One ampere (A) is one colomb per second.
What is the symbol for current?
I (capital i)
What is one thousandth of an ampere called? What symbol?
A milliampere.
mA.
What is one millionth of an ampere called? What symbol?
A microampere.
uA.
What are volts? How are they abbreviated?
A unit of measurement for the work needed to put a charge onto a body by adding electrons to it.
Abbreviated as V.
What is potential energy?
The electrons on a charged body.
What is voltage? How is it abbreviated?
The difference in potential between two points.
E.
What is an mV?
A millivolt. A thousandth of a volt.
What is a uV?
A microvolt. A millionth of a volt.
What is an insulator?
A poor or non-conductor. A material where the valence electrons are difficult to dislodge.
What are the three best conductors?
Silver, copper, and aluminum.
What purpose does gold serve in electronic circuits?
Corrosion resistance.
What is plasma? Is it a good conductor?
A gas composed of ionized molecules.
Yes, very good.
How is the tolerance of a component expressed?
The percentage of a marked value.
What is tolerance?
The maximum permissible variation from a stated value.
What is the unit of resistance? What symbol for a unit of resistance?
Ohms. Symbolized by the Greek letter Omega.
What is the symbol for resistance?
R.
What is an Ohm?
The resistance of a conductor that will allow one ampere of current to flow when one volt is applied to that conductor.
What causes the heating of a wire while current passes through it?
The resistance of the wire to electrons being forced to flow through it.
What are watts the measure of? And what is the abbreviation?
Watts are the measure of the amount of heat a resistor can tolerate before it burns up.
A watt is abbreviated as W.
What factors effect a wife’s ability to conduct an electrical current?
Specific resistance, length, diameter, and temperature.
What is the difference between fixed, tapped, and variable resistors?
Fixed has a constant value, tapped has several connections with different values, and variable has a movable tap to allow for a range of values.
What are two types of fixed or variable resistors?
Composition and wire-wound resistors.
What is the acronym for resistor colour code bands?
Better Be Ready Or Your Great Big Venture Goes West
Black
Brown
Red
Orange
Yellow
Green
Blue
Violet
Grey
White
What do the bands on a resistor stand for?
1 - First digit of resistance value
2 - Second digit of resistance value
3 - Multiplier (silver for 0.01, gold for 0.1)
4 - Tolerance
What is conductance? What is the name for a unit of conductance?
The reciprocal of resistance.
Siemens, abbreviated as S.
How is conductance expressed in an equation?
G.
What is an insulator?
A substance with such low conductance that effectively no current can flow through it.
True or False: Magnets have much in common with electrical conductors.
True
In relation to magnetic fields, in the 1800’s it was discovered that electrical current can be made to flow in a conductor by doing what?
- Moving the conductor through a magnetic field;
- Moving a magnetic field around a conductor; and
- Moving both the conductor and the magnetic field.
The electrical current in a moving conductor is at a maximum when the conductor is ____________ to the lines of force of the magnetic field?
Perpendicular.
Lines of force in a magnetic field run from which point to which?
The north and south pole outside the magnet, then returning south to north inside.
What are two types of magnets?
Permanent, made of iron or alloys of steel, and temporary, which are maintained by external forces.
What is an electromagnet?
A coil of wire wrapped around a solf iron core. When a current is applied to the wire coil, a magnetic field is generated in the core.
