electric fields
area around a charged object
it can push or pull other charges
magnetic fields
area around a magnet or moving charge
ex. magnet attracting paper clips
gravitational fields
area around an object with mass
ex. earth pulls everything downward
electrical energy
energy from moving electric charges
caused by electrons flowing through a circuit
ex: a battery powering a light bulb
mechanical energy
energy of motion and position
includes kinetic (movement) and potential (stored) energy
ex: a moving car
electric current
closed loop that lets electric current flow
needs a power source, wires, and a load (like a bulb)
if the loop is broken, current stops
series circuits
components connected one after another
current has only one path
if one part breaks, everything stops
parallel circuits
components connected on separate branches
current has more than one path
if one branch breaks, others still work
transformers
device that changes voltage
uses two coils and a magnetic field
can step voltage up or step it down
dc power
electric charge flows in one direction only
*ex: battery powering a flashlight
ac power
electric charge changes direction periodically
ex: electricity from wall outlets
step up transformer
if secondary coil has more loops voltage is stepped up
step down transformer
if it has fewer loops voltage is stepped down
radio waves
travels through space carrying signals
ex: used for radio, TV, and Wi-Fi
microwaves
can heat food and carry signals
ex: microwave ovens, Wi-Fi, and radar
ultraviolet (UV)
can cause sunburn and help make vitamin D
ex: sunlight, black lights
gamma rays
can penetrate materials and damage cells
ex: used in cancer treatment and radioactive decay
sun gives off many types of EMR
radio waves, infrared, visible light, UV, x-rays, gamma rays
most radiation
is absorbed by earth’s atmosphere
which EMR reach earth
visible light, some radio waves, and little infrared
refraction
bending of light when it passes from one medium to another
happens because light changes speed
ex: straw looks bent in a glass of water
diffraction
bending of waves around obstacles or through gaps
more noticeable with small openings or long wavelengths
ex: water waves spreading after passing a narrow gap
polarization
alignment of light waves in one direction
reduces glare by blocking certain light orientations
ex: polarized sunglasses blocking reflected sunlight
refracting telescope
uses lenses to bend light
