Answer:
105.6857 nm
Explanation:
Wave length of laser pointer = λ = 685 nm = 685×10⁻⁹ m
Distance between screen and slit = L = 5.4 m
Width of bright band = 2x = 7 cm
⇒x = 3.5 cm = 3.5×10⁻² m
The first minimum occurs at
sin θ = λ/d
θ = λ/d (since the angle is very small, sin θ ≈ θ)
Width of slit
d = λL/x
⇒d = 685×10⁻⁹×5.4/3.5×10⁻²
⇒d = 1056.857×10⁻⁷ m
∴ The width of the slit is 105.6857 nm
