Physics#2, Final Reviews

Front 1

Electroscope

Back 1

*an instrument used to detect charged objects.

Front 2

calculate electric force

Back 2

F= qE
force= charge x electric field

Front 3

force to distance

Back 3

*the strength of a field decreases the farther you get from the source.
Inverse square law-because the intesity diminishes as the square the distance increases.

Front 4

Like charges?

Back 4

repel

Front 5

Unlike charges?

Back 5

attract

Front 6

Define charging by induction

Back 6

*A moving magnet induces electric current to flow in a circuit.
*Fardays Law of induction- voltage is proportional to the rate of change in the magnetic field through the coil.

Front 7

Define Polarization

Back 7

*seperation of the positive and the negative change in an objects atoms due to the effect of an elctric field.

Front 8

Where are magnetic fields the strongest?

Back 8

If the field lines are close they are stronger.

Front 9

What direction do magnetic field lines point?

Back 9

*magnetic field lines always point away from the north pole and toward the south pole

Front 10

How or why does an electric motor spin?

Back 10

*as the rotor spins, the cummutator reverses direction of the current in the electromagnet.

Front 11

Define generator

Back 11

*converts kinetic energy into electrical energy using the law of induction.

Front 12

Define wavelength

Back 12

*the length of one complete cycle of a wave.

Front 13

Define hertz

Back 13

*unit of 1 cycle per second. Frequency measured in hertz.

Front 14

Define period

Back 14

*the time it takes to repeat 1 cycle.

Front 15

Define absorption

Back 15

*the decrease in amplitude of a wave as it passes through material and loses energy.

Front 16

Define longitudinal waves

Back 16

* a wave that has oscillations in the same direction as the wave travels.

Front 17

Define transverse wave

Back 17

*a wave with oscillation that are perpendicular to the direction the wave travels.

Front 18

Define closed circuit

Back 18

*circuit with a complete path for the current to flow.

Front 19

What is color?

Back 19

*the perception of energy of light.
*red-lowest energy
*violet-highest energy

Front 20

Define fuse

Back 20

*each parallel circuit has a "fuse" or a circuit breaker to stop the current if it exceeds the safe amount.

Front 21

Define watt

Back 21

*unit of power

Front 22

Define circular waves

Back 22

*wave crests form a pattern of circular wave fronts.

Front 23

Define plane waves

Back 23

*wave crests form a pattern of stright line wave fronts.

Front 24

Inverse square law rule in regards to light waves.

Back 24

*describes a quantity that varies inversely with the square of the distance.

Front 25

Define transformers

Back 25

*A device that uses induction to convert AC electrical current and voltage to another AC current and voltage while keeping the power about the same.

Front 26

Define interference

Back 26

*a pattern of pressure, brightness, amplitude or other wave characteristic that comes from adding more than one wave of the same kind.

Front 27

Define refraction

Back 27

*the bending of a wave as it travels across a boundry.

Front 28

Define reflection

Back 28

*the wave bouncing off a surface.

Front 29

Define frequency

Back 29

*the number of cycles per second, measured in hertz (Hz)

Front 30

Radio Waves

Back 30

*radio waves-lowest frequency of electromagnetic waves with a wavelength greater than tens of centimeters.
*example: 101.1 radio station means that the broadcast is = to 101 megahertz.

Front 31

How does changes in force relate to distance?

Back 31

*the force from a magnet decrease faster than an inverse square law. This is because all magnets have two opposite pole, not one.

Front 32

What does an increase in the number of wires in a magnetic field do?

Back 32

*a single wire can be looped into a coil, concentrating the magnetic field at the coil's center.
*when a wire is in a circular loop, field lines on the inside of the loop squeeze together.
*the most common form of electromagnetic device is a coil with many turns called, "solenoid"

Front 33

Standing Wave

Back 33

*a wave that is confined in a space.
*standing waves include sound, water, and light.

Front 34

Sound Wave

Back 34

*anything that vibrates creates sound waves, as long as there is contact with other atoms.
*not all sounds can be heard.
*humans can hear between 20 Hz and 100,000 Hz.
*sound is a traveling oscillation of atoms.

Front 35

List primary colors from the lowest to the highest energy
*see page 486

Back 35

red-460
orange-490
yellow-520
green-570
blue-640
violet-750

Front 36

Series Circuit

Back 36

*contains only one path for electric current to flow.
*current is the same at all points in the circuit.

Front 37

Parallel Circuits

Back 37

*a circuit with more than one path for the current.
*each path in the circuit is called a branch.
*all of the current entering a branch point must exit again. The rule is known as Kirchhoff's Current Law

Front 38

Short Circuit

Back 38

*a parallel path in a circuit with very low resistance.
*example diagram on page 326.

Front 39

Electric companies

Back 39

*they do not change by the volt, amp or ohm. They charge by the unit=watt.
*electric companies charge by how many Kilowatts hours are used during a period of time.
*one kilowatt means that power has been used for one hour.

Front 40

Calculate current in volts

Back 40

P=IV
power/watts= current X Voltage