Physics Test #1 Flashcards
Forms of light & how they work
Incandescence: light produced by an object
Fluorescence: glass tube filled with gas
Phosphorescence: stores energy from a source of light then emits it slowly over a long time
Chemiluminescence: light produced from a chemical reaction without a rise in temp
Bioluminescence: ability of a plant or animal to produce light
Triboluminescence: light produced from friction
LED: electroluminescent light source made out of a diode, use a small amount of electricity, and radiate little heat
7 parts of the electromagnetic spectrum & examples
-radio (Bluetooth)
-microwave (traffic speed cameras)
-infrared (remotes)
-visible (neon lights)
-ultraviolet (black lights)
-x-ray (bone density scan)
-gamma ray (medicine)
How does light travel as both a wave and a particle
Light behaves as a wave and as a particle depending on the situation.
-when light travels in space, it travels in waves
-when near us, it travels in straight lines
-the human eye can only see light in a straight line
Explain the relationship between wavelength and frequency
The shorter the wavelength, the higher the frequency. They are proportional to each other.
KNOW THE CHART**
If a wave has a frequency or 6 cycles per second and a wavelength of 15cm what is the speed of the wave?
6cycles/sec x 15cm =90cm/sec
Briefly describe the difference between diffuse reflection and specular reflection
Specular (smooth surfaces): light rays reflect at the same angle
Diffuse (rougher surfaces): scatters light rays in different directions
Additive colour theory
-transmitted light
-white light is composed of all colours
-mix the three primary colours (red, green, blue) to make white light
-mix only 2 of the primary colours to make a secondary colour
Subtractive colour theory
-absorption of light
-when a light wave strikes an object, some wavelengths of light reflect, and some are absorbed
-the colour seen when looking at an object depends on the wavelengths
that are reflected back to your eyes
How are the primary and secondary colours different? When do we use them?
Primary (Red, yellow, blue): cannot be produced by mixing other colours
(used to create other colours)
Secondary (orange, green, purple): can be produced by mixing other colours (used in the study of light and colour mixing)
If a red balloon is in a room that only has magenta light what colour would the balloon appear?
-magenta is a combination of red and blue light
-red balloon reflects red wavelengths
-since magenta contains red, the balloon would reflect most of the red light and appear red under magenta light
How do shadows work? What does the size of the source of light have to do with the shadows produced?
A shadow forms when an opaque object blocks light rays from a source.
Small light source: sharp & well defined shadows
Large light source: no sharp edges on the shadow
Umbra: all light rays are blocked
Penumbra: area of partial shadow
If a red balloon is in a room that only has green light what colour would the balloon appear?
-green light contains only green wavelengths
-red balloon reflects red wavelengths
-since there is no red light being emitted, the balloon appears black or very dark, as it can’t reflect green light
