Diffraction Grating

Question 1

Why use a laser or 2nd slit for any other light source?

Answer 1

So only monochromatic light travels through the double slit / diffraction grating (as light travels in a straight line only)

Question 2

What is a ‘coherent’ light source?

Answer 2

Light of a constant / fixed phase difference

Question 3

How are fringes formed?

Answer 3

From constructive / destructive interference represented on a screen (of which the diffracted light should be traveling to)

Question 4

What is the equation related to diffraction grating?

Answer 4

nλ = dsinθ

Where: 
n = nth order (always an integer)
λ = Wavelength of light [m]
d = Space between diffracted light [m]
θ = Angle between central path and nth order light

Question 5

How do you increase the wavespread of diffracted light?

Answer 5

> Use a smaller slit size

> Increase the wavelength (distance between wavefronts)