18.1 Electromagnetic Waves

What are electromagnetic waves?

Transverse waves that consist of changing electric fields and changing magnetic force

Circle the letter of each sentence that is true about electric and magnetic fields: A. An electromagnetic wave occurs when electric and magnetic fields vibrate at right angles to each other B. A magnetic field is surrounded by an electric current C. Changing electric and magnetic fields regenerate each other D. Electromagnetic waves are produced when n electric charge vibrates

a, c

Circle the letter of each sentence that is true about electromagnetic waves A. different electromagnetic waves can have different frequencies B. wavelength is directly proportional to frequency C. electromagnetic waves always travel at the speed of light D. all electromagnetic waves travel at the same speed in a vacuum

a,d

The closer you get to a source of light, the _________ the light appears

brighter

As the wavelengths of electromagnetic waves increase, the frequencies ______, for waves moving in a _______.

decrease, vacuum

The transfer of energy by electromagnetic waves traveling through matter or across space is called _______

electromagnetic radiation

As a thunderstorm approaches, you see the lightning before you hear the thunder, because light travels ______ than sound

faster

As protons travel farther from the source, the _________ of the light decreases.

intensity

Blue light has a higher frequency than red light, so photons of blue light have ______ energy than photons of red light.

more

Interference only occurs when two or more waves overlap, so ________ experiment showed that light behaves like a _______

particles, wave

The emission of electrons from a metal caused by light striking the metal is called the _____________ effect.

photoelectric

Intensity is the ________ at which a wave's energy flows through a given unit of area

rate

Electromagnetic radiation behaves sometimes like a ____________ and sometimes like a stream of _________

wave, particles

Circle the letter that gives the correct speed of light in a vacuum A. 3.00 x 10 kilometers per second B. 3.00 x 10 meters per hour C. 3.00 x 10 meters per second D. 3.00 x 10 kilometers per hour

C

Travels through a vacuum Travels through a medium Fits wave model Fits practicle model Transverse wave Longitudinal wave

E B B E B M

Electromagnetic waves are produced when ___ vibrates or accelerates

Electric charge

Electric fields are produced by electrically charged particles and by changing ____, and by vibrating charges.

Electric fields

Is the following true or false? Electromagnetic waves need a medium to travel through

False