Answer:
a) laser 1 has the maximum closest to the central maximum
b) y₂ –y₁ = L 1.66 10⁻²
Explanation:
a), B1, B2) The expression that describes the constructive interference for a double slit is
d sin θ = m λ
The pattern is observed on a screen
tan θ = y / L
Since the angles are very small
tan θ = sin θ / cos θ = sin θ = y/L
d y / L = m λ
In this case the laser has a wavelength
λ ₁ = d/20
We substitute
d y / L = m d / 20
m = 1
y₁ = L / 20
For the laser 2 λ ₂= d / 15
y₂ = L / 15
When examining the two expressions, laser 1 has the maximum closest to the central maximum
b) the difference between the two patterns is
y₂- y₁ = L (1/15 - 1/20)
y₂ –y₁ = L 1.66 10⁻²
C) laser 1 second maximum
y₁ ’= 2 L / 20
y₁ ’= L 0.1
Laser 2 third minimum
To have a minimum, the equation must be satisfied
d sin θ = (m + ½) λ
d y / L = (m + ½) λ
d y / L = (m + ½) d / 15
y = L (m +1/2) / 15
m = 3
y₂’= L (3 + ½) / 15
y₂’= L 0.2333
The difference is
y₁ ’- y₂’ = L (0.1 - 0.2333)
y₁ ’–y₂’ = L (-0.133)