The wave nature of light Flashcards
What is the relationship between the size of the gap the light diffracts through and its wavelength?
The closer the the gap size is to the wavelength, the more diffraction occurs.
How do you calculate the grating constant (m) of a diffraction grating?
It is the inverse of the number of lines per metre the grating has.
(d = 1/N)
Describe an experiment to demonstrate the presence of UV and IR.
Shine white light through a grating so it disperses onto a screen.
Put a thermometer next to the red end of the spectrum, a heating effect occurs.
Put a piece of paper with some vaseline next to the violet end, it should glow.
What is the function of the heavy base of the spectrometer?
It keeps the instrument steady.
What is the function of the vernier scale?
It is used to measure angles of deviation (for use with the formula - theta).
What is the function of the the turntable and levelling screws?
The turntable allows for positioning and the levelling screws are for adjustment.
What is the collimator for?
The collimator is a slit through which the light passes and where a convex lens focuses the light onto a grating.
(The light is collimated, made into parallel rays, here)
What is the telescope for?
It is a viewing scope used for looking at the fringes of light.
It consists of two convex lenses, an eyepiece and an objective lens and may have cross threads.
Explain what is involved in Young’s double slit experiment.
A monochromatic light source is placed behind a slit.
The light diffracts, and meets two more slits and diffracts again, producing two coherent sources which will interfere.
Constructive interference produces bright fringes on the screen while destructive produces dark fringes.
