Resultant Intensity in Interference (I = I₁ + I₂ + 2√(I₁I₂)cosφ)
jee-mainjee-advancedneet-ug
I = I₁ + I₂ + 2√(I₁I₂)cosφ
What each symbol means
| Symbol | What it stands for |
|---|---|
| I | Resultant intensity at a point |
| I_1 | Intensity due to source 1 alone |
| I_2 | Intensity due to source 2 alone |
| \varphi | Phase difference between the two waves at that point |
When to use this
Coherent sources only. I_max = (√I₁ + √I₂)² at φ = 0, 2π, 4π,... I_min = (√I₁ - √I₂)² at φ = π, 3π, 5π,... For equal intensities: I = 4I₀cos²(φ/2).