Shortcut Methods
Shortcut Methods and Tricks to Solve Numerical Problems on Interference of Light
Double-Slit Interference
- Fringe width:
where (\beta) is the fringe width, (\lambda) is the wavelength of light, (D) is the distance from the slits to the screen, and (d) is the slit separation. - Separation of bright fringes:
- Intensity distribution:
where (I_0) is the maximum intensity and (x) is the distance from the central fringe.
Michelson Interferometer
- Wavelength of light
where (D) is the path difference and (N) is the number of fringes observed. - Coherence Length
where (l_c) is the coherence length and (\Delta \lambda) is the spectral bandwidth of the light source.
Young’s Double-Slit Experiment
- Fringe spacing
where (x) is the fringe spacing, (\lambda) is the wavelength of light, (D) is the distance to the screen, and (d) is the slit separation. - Fringe width
where (\beta) is the fringe width. - Total Number of fringes:
Coherence and Incoherence
- Coherent sources: Emit waves with the same frequency, constant phase difference, and a definite phase relation.
- Incoherent sources: Emit waves with random phase differences and no definite phase relation.
Thin Film Interference
- Condition for constructive interference:
- Condition for destructive interference:
where (t) is the film thickness, (n) is the refractive index of the film, (\lambda) is the wavelength of light, and (m) is the order of interference.