Physics Vocabulary:Term I

prefixes for metric system

deci = one tenth centi= one hundredth milli = one thousandth Kilo= thousand Yotta= 10^24 (10 to the 24 power)

Gamma Waves

gamma wave is a pattern of neural oscillation in humans with a frequency between 25 to 100 Hz, They have a high frequency and a very short wavelengths also form of X-Ray

(Total Internal Reflection)

the complete reflection that takes place within a substance when the angle of incidence of light striking the surface boundary is less than the critical angle

yotta

10 to the 24th power 1 000 000 000 000 000 000 000 000

Transverse Wave

A wave with vibration at right angles to the direction the wave is traveling

Incident Ray (Ray of Incidence)

The Ray of light that travels from the object to the reflecting surface

laser

A concentrated beam of light with only one wavelength

Penumbra

A partial shadow that appears where light from part of the source is blocked and light from another source is not blocked

Longitudinal Wave

A wave in which the vibration is in the same direction as that in which the wave is traveling, rather than at right angles to it

Angle of Refraction

The angle between the ray of refraction and the normal

Constructive Interference

Addition of two or more waves when wave crests overlap to produce a resulting wave of increased amplitude

Angle of Reflection

Angle between a reflected ray and the normal to a surface

Angle of Incidence

Angle between an incident ray and the normal to a surface.

Destructive Interference

Combination of waves where the crests of one wave overlap the troughs of another wave resulting in a wave of decreased amplitude

Infrared Waves

Electromagnetic Waves of frequencies lower than red visible light are called infrared light

Period

In general the time it takes to complete a single cycle

Snell's Law

Index of Refraction (of substance) x Sin(angle of substance) = Index of Refraction (of another substance) x Sin(angle of another substance)

Reflected Ray (Ray of Reflection)

The Ray of light that is reflected form the reflected surface to the eyes

Micro Waves

Microwaves are electromagnetic waves with wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz. Microwaves are very short radio waves that travel in an invisible circular motion through the air. Microwaves go faster than television waves but slower than infrared rays (microwaves travel at the speed of light, 186,282 miles per second!). They are stronger than radio frequency waves, but weaker than X-rays.

Radio Waves

Radio waves have the longest wavelengths in the electromagnetic spectrum but the slowest frequencies

Slinky

Slinky or "Lazy Spring" is a toy consisting of a helical spring that stretches and can bounce up and down.

Metric Prefix

Syllable or group of syllables attached to the beginning of a metric unit in order to make the unit larger or smaller.

Virtual Ray

The "ray" of light behind the mirror; there is no ray really there. It is the ray we draw to make sense of how things work

EM Spectrum Electromagnetic Spectrum

The Electromagnetic Spectrum is a continuous range of waves extending from radio waves to gamma waves. Waves are the same in nature but differ in frequency and wavelength

Diffraction

The bending of a wave around a barrier, such as an obstacle or the edges of an opening

Umbra

The darker side of a shadow where all the light is blocked

Amplitude

The distance from the midpoint to the maximum (crest) of a wave or equivalently from the midpoint to the minimum (trough)

Wavelength

The distance from the top of a crest of a wave to the top of the following crest, or equivalently, the distance between successive identical parts of a wave

Hypotenuse

The hypotenuse is the side opposite the right angle

Law of Reflection

The law of reflection states that when a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection

Light Waves

The light we can see. The lowest frequency of light that we can see is red. The highest visible frequencies are nearly twice the frequency of red and appear violet

Frequency

The number of events( cycles, vibrations, oscillations, or any repeated event) per time; measured in hertz: Inverse of period

normal

The perpendicular line to the reflective or the refractive surface

Sine(angle)

The ratio of the length of the side opposite the angle over the length of the hypotenuse.

Refracted Ray (Ray of Refraction)

The ray of light that is refracted through a substance to the eyes

Wave Speed

The speed of a wave depends on the medium it travels through. Whatever the medium the speed, frequency, and wavelength of the wave are related: wave speed = wavelength x frequency The equation is: Speed = wavelength x frequency (v=λf)

The Index of Refraction

The velocity at which light moves in a substance compared to air in any given substance. Th higher the number the denser the substance

reflection from free end

This is reflection against a medium that is free to move. Note that in this case, the pulse is NOT inverted.

reflection from fixed end

This is reflection from an obstacle. The pulse is inverted.

Laser Slit experiment ( or Double Slit experiment

Thomas Young"s double slit experiment was extremely important in wave theory and proved light traveled in waves

Ultraviolet waves

Type of X-Rays that have high frequency and short wavelengths

Metric System

a decimal system of weights and measures based on the meter and the kilogram and the second. This system was originally established in France in the 1790s

Light Ray

a line of light

Pythagorean Theorem

a²+b²=c² The Pythagorean Theorem stated algebraically is: for a right triangle with sides of lengths a, b, and c, where c is the length of the hypotenuse.

centi

hundredth

Medium

the material through which a wave travels

Adjacent

the side of a right triangle that touches the current angle that isn't the hypotenuse

Opposite

the side opposite the current angle

object

the thing that is reflected in the mirror

image

the virtual object

Kilo

thousand

milli

thousandth

Lifeguard Metaphor

when light refracts it takes the fastest route not the shortest route