Question

Distance of the third bright fringe from the central maxima on the screen for \( 5000 \, \text{Å} \) wavelength.

Hint:

The position of bright fringes increases linearly with the wavelength and the order of the fringe in the double-slit experiment.

Answer 1

Step 1: Condition for Bright Fringe in Double Slit Experiment.
The condition for the bright fringe in a double-slit experiment is given by: \[ d \sin \theta = m \lambda \] For the third bright fringe, \( m = 3 \).
Step 2: Finding the Distance for the Third Bright Fringe.
Using the same approximation as before: \[ d \times \frac{y}{L} = 3 \lambda \] \[ y = \frac{(3 \times 5000 \times 10^{-10} \, \text{m}) \times 1.0 \, \text{m}}{1.0 \times 10^{-3} \, \text{m}} = 1.5 \, \text{mm} \] Thus, the distance of the third bright fringe from the central maxima is \( 1.5 \, \text{mm} \).