Unit Test #2 - Mrs. Williams

GSCI-2010: Physical Science for Educators

Basic Properties of Waves

Waves are disturbances that transfer energy from place to place

Many require a medium to travel through

Waves only move energy

Mechanical Waves

Requires a medium

Two Types: Transverse and longitudinal

Transverse Waves

Move the medium at right angles to the direction of the wave movement

Longitudinal Waves

Move parallel to the direction of the wave movement

Parts of a Transverse Wave

1. Wavelength

2. Trough

3. Amplitude

4. Crest

Parts of a Longitudinal Wave

1. Compression

2. Rarefaction

3. Wavelength

4. Amplitude

Amplitude in Waves

Transverse Wave - Maximum distance the medium moves up and down from its rest position

Longitudinal Wave - Measure of how compressed the compression is

Wavelength in Waves

Transverse Wave - Distance from crest to crest or trough to trough

Longitudinal Wave - Distance from compression to compression or rarefaction to rarefaction

Frequency in Waves

The amount of complete waves that pass a certain point in a certain amount of time and are measured in Hertz

The Electromagnetic Spectrum

Radio, microwave, infrared, visible light, UV, x-ray, gamma ray

Red - longest wavelength/lowest frequency

Violet - shortest wavelength/highest frequency

When Light Strikes an Object

Light can be transmitted, reflected, or absorbed

How Light Passes Through

Transparent - All light passes through

Translucent - Some light passes through

Opaque - No light passes through

Reflection

Diffuse - Light bounces off in many different directions (Bumpy surface)

Specular - Light bounces off at a predictable angle (Flat surface)

Refraction

Light bends as wave changes speed and enters or exits into a new medium (Ex: Pencil in water)

Why we see Different Colors

The color of different objects is determined by the wavelengths of light that an object reflects and absorbs

Light to Heat Transfer

Black objects absorb all colors and transfers to thermal energy

Types of Mirrors

Plane - A flat mirror that produces an image upright and of the same size

Concave - A mirror that curves inward

Convex - A mirror that curves outward

Types of Lenses

Concave - Thinner in the center and causes light to diverge (spread out)

Convex - Thicker at the center and causes light to converge (come together)

Sound is….

vibration

How Sound Travels

Travels fastest in solids and warm air and slowest in gases and cold air

Intensity

Amount of energy a wave carries and how loud it is (Decibals)

Pitch

The human perception of the frequency of sound

The Doppler Effect

The change in frequency of a wave as its source moves in relation to the observer

Instruments and Pitch

The larger the object, the lower the pitch (tuba, bass drum)

The smaller the object, the higher the pitch (trumpet, snare drum)

Reverberation

The reflection of sound waves

Echo

When sound reflection is repeated

Practical Uses of Reverb/Echo

Sonar - Uses the reflection of sound waves to located objects under water

Echolocation - Used by bats and whales for food

Sonogram - Used to create images from reflected sound

Acoustics

The study of how sounds interact with each other and the environment

Resonance

When a material or object is made to vibrate at its natural frequency

Magnetism

Occurs because of electrons spinning in the same direction

Electricity

Occurs because of difference in charges in atoms

North and South Poles

Opposites attract, same sides repel

Charge of an Atom

More Protons (+)

More electrons (-)

Same amount (neutral)

Insulators vs. Conductors

Insulators - do not allow electricity to travel

Conductors - allow electricity to travel

Electric Force

An attraction or repulsion like and unlike charges have for each other

Static Cling

When two objects rub together, one loses some of its electrons to the other, causing attraction

Electric Discharge

The rapid movement of excess charge from one object to another

Units of Electricity

Amps - Measurement of the rate of flow of an electric current

Volts - Measure of the amount of electrical potential energy

Ohms - Measure of how difficult it is for electricity to flow

Watts - Measure of the rate of energy use or power

Circuit Basics

Parallel - A circuit that provides more than one path for electricity flow

Series - A circuit that provides one path for electricity flow

Resistance is Dependent on….

Type of material

Length of the conductor

Width of the conductor

Initial voltage