EXAM #8 — PHYSICS UNIT 01

Question 1

define: electricity (electric current).

Answer 1

electrons moving in a conductor

Question 2

define: ampere.

Answer 2

unit measure of current flow

Question 3

define: electric field.

Answer 3

continuous lines of force that radiate from a positive to negative charge

Question 4

define: electrical potential energy (electromotive force or EMF).

Answer 4

the potential energy created by the attractive or repulsive forces of electric charges

Question 5

define: impedance.

Answer 5

the conversion of electricity to another form of energy in a circuit

Question 6

define: resistance.

Answer 6

the type of impedance wherein electricity is converted to heat

Question 7

define: capacitance.

Answer 7

the type of impedance wherein electricity is converted to an electric field

Question 8

define: direct current (DC).

Answer 8

current that flows in only one direction in a circuit

Question 9

define: alternating current (AC).

Answer 9

current that alternates between both directions of flow in a circuit

Question 10

define: magnetic field.

Answer 10

continuous lines of force that radiate from the north pole of a magnet to the south pole

Question 11

define: electrodynamics.

Answer 11

the study of moving electrical charges

Question 12

define: electromagnet.

Answer 12

a conductor that is wound many times and carries an electric current, which creates a magnetic field

Question 13

define: magnetic domain.

Answer 13

the smallest unit of magnetism

Question 14

define: magnetic susceptibility.

Answer 14

the degree to which an object is affected by a magnetic field

Question 15

define: Tesla.

Answer 15

a standard unit of measure for magnetic field strength

Question 16

define: Gauss.

Answer 16

a standard unit of measure for magnetic field strength

Question 17

define: phase.

Answer 17

the degree to which waveforms cross a center point in the same direction at the same time or the distance in degrees between the angles of the waveforms

Question 18

define: electromagnetic induction.

Answer 18

the transfer of energy between electrical and magnetic fields- specifically the ability of a moving magnetic field to induce an electrical current in a circuit

Question 19

define: electromagnetic radiation.

Answer 19

electric and magnetic fields oscillating perpendicular to and 90° out of phase with each other

Question 20

describe how distance affects the strength of interaction between electrostatic charges.

Answer 20

inversely square; as the distance between the charges doubles, the strength of the interaction is divided by four

Question 21

state Ohm’s law and/or express it as a formula.

Answer 21

V=IR

Question 22

describe and distinguish between an insulator, conductor, semiconductor, and superconductor.

Answer 22

insulators resist electric current;

conductors carry current with impedance;

semiconductors can be made to carry or resist current;

superconductors carry current with little or no impedance

Question 23

describe and distinguish between ferromagnetism, paramagnetism, and diamagnetism.

Answer 23

ferromagnetism means objects are highly susceptible to magnetic fields;

paramagnetism means they are slightly susceptible;

diamagnetism means they are not susceptible or slightly negatively susceptible

Question 24

describe and distinguish between temporary and permanent magnets.

Answer 24

temporary magnets lose their magnetism when they are not near an external magnetic field,

permanent magnets retain their magnetism when not near an external magnetic field

Question 25

describe how like and unlike magnetic poles interact.

Answer 25

like poles repel, unlike poles attract

Question 26

describe how distance affects magnetic field strength.

Answer 26

inversely square; as the distance from the field doubles, the strength is divided by four

Question 27

compare the two standards of measure for magnetic field strength.

Answer 27

1 Tesla = 10,000 Gauss

Question 28

state Faraday’s Law of Electromagnetic Induction.

Answer 28

a changing magnetic field can induce a current in a conductor.

Question 29

identify the 3 types of impedance.

Answer 29

resistance, capacitance, inductance

Question 30

identify the physical cause of electromagnetic radiation.

Answer 30

electric and magnetic fields oscillating perpendicular to and 90 ° out of phase with each other

Question 31

describe the orientation of magnetic domains in a magnet.

Answer 31

roughly aligned

Question 32

explain how the magnetic field is affected if a current-carrying wire is looped.

Answer 32

the magnetic field is intensified in the center of the loop

Question 33

describe the orientation of an induced magnetic field to the moving electrical charge.

Answer 33

the magnetic field is perpendicular to the direction of the moving charge

Question 34

identify the 2 types of changes in a magnetic field that can induce current into a circuit.

Answer 34

directional or velocity changes

Question 35

describe the positions of two waveforms when they are in phase, 90° out of phase, and 180° out of phase

Answer 35

exactly the same time and the crests and troughs are superimposed;

waveforms 90° out of phase will not cross a center point at the same time, and the crests and troughs do not overlap;

waveforms 180° out of phase will cross a center point at the same time, but the crests and troughs are opposite of each other.