exam 4 - electromagnetic spectrum

what did maxwell show about light, and what is maxwell’s speed of light equation

showed light is a electromagnetic wave

what wavelengths are the human eye sensitive to?

400nm-700nm

in 1849, what did Fizeau successfully measure?

speed of light

which has more of an effect, the energy carried by an electromagnetic wave or its momentum?

energy

what device inside of a microwave oven creates the microwaves?

cavity magnetron

what did Hertz contribute to our understanding of electromagnetic waves?

verified Maxwell’s predictions by generating and detecting electromagnetic waves in lab and observed the photoelectric effect.

what is the purpose of a thin film coating on a solar cell?

to minimize reflected light and maximize absorption

how are radiowaves made?

from electric dipole antennas

how are infrared waves made?

heating things up causing molecules to vibrate producing infrared radiation

how is visible light made?

heating things up until they glow. light emitting diodes for example

how are UV waves made?

heat, blocking out visible and IR

how are x-rays made?

By accelerating electrons and knocking out core electrons e⁻ from the outer shell which drops down a level, emitting x-rays

how are gamma rays made?

nuclear processes

explain how gradient coils work in an MRI and what happens if they're turned on or off

they're solenoids that move inside MRI machines that turn off and on loudly. When on, the magnetic dipoles are aligned but slightly off center. When off, they realign, but it takes time, emitting radio waves. detection coils sense radio waves, processing this info into an image

describe EM waves in a vacuum, with relationships of the electric and magnetic fields relative to each other and the direction of propagation. Describe relationships between E and B fields; wavelenght, frequency and speed. who derived these equations?

what is intensity in fundamental units

kg/s³ (W/m² = kgm²/m²s³)