Particle and Waves: 7 - Spectra Flashcards
What is the definition of irradiance?
Irradiance is a measure of the energy falling on a surface per unit time or the power per unit area.
or
Irradiance is the power per unit area incident on a surface.
What is the equation for irradiance?
I = P/A
What is irradiance measured in?
Wm-2
What are facts about irradiance and laser light?
The light from a laser is monochromatic, coherent, irradiant and forms a paralell beam.
Due to the fact that the beam is irradiant and parallel what does this mean that the laser is?
A potetial eye hazard.
What is irradiance inversley proportional to?
the square of the distance from a point source.
Describe an experiment to verify the inverse square law from a point source?
Aim: To investigate the relationship between the light intensity with the distance away from a point source of light.
Apparatus: Phone light meter, torch and metre stick.
Method: hold the phone at the start of the metre stick and hold the torch at the end/1 metre point of the stick. Measure the light intensity and record this data on a table. Repeat the experiment by decreasing the distance and recording the light intensity at each point and plot a graph of the results.
Conclusion: As distance increaces the light intensity/irradiance decreaces.
What is the equation for irradiance and distance?
I1 x d1 ² = I2 x d2² or I = k/d²
What is ground state?
The first energy/ionisation level of an atom.
What is an electron said to be in the ionization state?
If the electron gains enough energy to be completely removed from the atom.
What is ground state also known as?
Eo
What does the further an orbit is from the nucleus mean the electron has?
More energy.
How much kinetic energy does an electron which has gained just enough energy to leave the atom have and what is this also called?
0J of kinetic energy. The ionisation energy.
AS an electron that has gained just enough energy to leave the atom has 0J of kinetic energy, what does this mean for the the electrons in lower energy levels have?
Negative energies associated with them.
What is emmision spectrum?
The range of colours given out by a light source.
