Light Waves & Photons Flashcards
What is a wave?
A wave is a continuously repeating change or oscillation in matter or in a physical field.
What is light?
Light is an electromagnetic wave, consisting of oscillations of electric and magnetic fields traveling through space.
What are the characteristics of a wave?
Wavelength and Frequency
What is the wavelength?
The distance between any two identical points on adjacent waves.
What is frequency?
The number of wavelengths that pass a fixed point in one unit of time.
c = f(lambda)
What is meant by the electromagnetic spectrum?
A Continuum of all electromagnetic waves arranged according to wavelength and frequency.
What is the;
a) Visible range in nm
b) Visible range in Hz
c) Red in nm
d) Violet in nm
a) 380nm - 750nm
b) 7.9 x 10^14 Hz - 4.0 x 10^14 Hz
c) ~700nm
d) ~450nm
What gives evidence of wave nature?
Diffraction - Spreading out when met with an obstacle about the size of the wavelength.
What is photoelectric effect?
The ejection of an electron from the surface of a metal or other material when light shines on it.
E = hf ( the energy of a light particle)
What is meant by particle-wave duality of light?
Light has both wave and particle properties (particle proved by photoelectric effect)
What is a line spectrum?
What is the connection with atoms? (atomic spectrum)
A line spectrum shows only certain colors or specific wavelengths of light.
When atoms are heated they emit light. This produces a line spectrum that is specific to the atom.
What is the line spectrum of H?
red, blue-green, blue, violet
What is an isotope?
each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei
