Diffraction Grating vs. Double Slit
Higher number of slits – Lower number of slits – just 2
usually 100’s per millimetre - - results in less light beams
results in more light beams contributing to the
contributing to the interference pattern
interference pattern Produces much more
Produces much sharper indistinct maxima (each
maxima (each order is order is blurred to a high
clearer and narrower) degree with a bright central
Constructive interference line)
occurs only at extremely Constructive interference
precise angles largely unclear
The maxima are brighter due The maxima are duller due to
to a high volume of waves a low volume of waves
constructively interfering constructively interfering
Darker fringes are more Darker fringes are less
pronounced and darker due pronounced due to lower
to higher levels of levels of overlapping
overlapping destructive destructive interference
interference Generates less accurate
Generates more accurate measurements and harder to
measurements and easier to measure maxima, it is
measure maxima, there is difficult to locate the centre
less uncertainty of the orders
Uses formula d sinθ = n λ Uses formula λ = x d / L
References: Diffraction Gratings Revision notes | A-Level Physics OCR |
Cognito (21:14, 15/01/2026), 3.3: Diffraction Gratings - Physics LibreTexts
(21:15, 15/01/2026), Multiple Slit Diffraction – Introductory Physics for the
Health and Life Sciences II (21:16, 15/01/2026)
Higher number of slits – Lower number of slits – just 2
usually 100’s per millimetre - - results in less light beams
results in more light beams contributing to the
contributing to the interference pattern
interference pattern Produces much more
Produces much sharper indistinct maxima (each
maxima (each order is order is blurred to a high
clearer and narrower) degree with a bright central
Constructive interference line)
occurs only at extremely Constructive interference
precise angles largely unclear
The maxima are brighter due The maxima are duller due to
to a high volume of waves a low volume of waves
constructively interfering constructively interfering
Darker fringes are more Darker fringes are less
pronounced and darker due pronounced due to lower
to higher levels of levels of overlapping
overlapping destructive destructive interference
interference Generates less accurate
Generates more accurate measurements and harder to
measurements and easier to measure maxima, it is
measure maxima, there is difficult to locate the centre
less uncertainty of the orders
Uses formula d sinθ = n λ Uses formula λ = x d / L
References: Diffraction Gratings Revision notes | A-Level Physics OCR |
Cognito (21:14, 15/01/2026), 3.3: Diffraction Gratings - Physics LibreTexts
(21:15, 15/01/2026), Multiple Slit Diffraction – Introductory Physics for the
Health and Life Sciences II (21:16, 15/01/2026)
