Which property of light ray does not change in refraction?

What is a ray of light?

What is a ray of light?

Classify materials on the baiss of their behaviour in a magnetic field. Under which cateogry does iron come? How does the magnetic property of iron change with increase of temperature?

What is refraction of light?

What is refraction of light?

Which of the following does not characterise X-rays?

Give the properties of cathode rays ?