जब किसी अपारदर्शी वस्तु पर प्रकाश आपतित होता है, तो हमें उसकी ज्यामितीय छाया दिखाई देती है। यह मुख्य घटना इसलिए होती है क्योंकि:

A ray of light travels from air into a glass slab. Which of the following physical quantities of light does not change during this process?

In the visible spectrum of light, which colour has the longest wavelength?

What is the approximate wavelength range of the visible spectrum of light?