Wave Optics

JEE Main level, single correct, medium

61 of 191

Question 61 of 191

A single slit of width aa is illuminated by a monochromatic light of wavelength 600nm600nm. The value of aa for which first minimum appears at θ=30o\theta ={30}^{o} on the screen will be :

Show answer and solution

Answer: (A) 1.2μm1.2\mu m

For the first minima
asin⁡θ=λa\sin \theta =\lambda
The given data is
θ=30∘λ=600nm\theta =30^{\circ} \lambda =600nm
The value of aa is
a=λsin⁡30∘=600×10−912=1.2μma=\dfrac{\lambda }{\sin 30^{\circ}}=\dfrac{600\times {10}^{-9}}{\dfrac{1}{2}}=1.2\mu m

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.
See it move: Wave optics: YDSE, diffraction and polarisation simulationDrag the sliders and watch the numbers in this question change.

More Physics practice

JEE Main Physics practice question on Wave Optics (Youngs Double Slit Experiment), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.