Question

how do you apply lens marker formula to detor mine the nature of air . bubbles in water

Answer 1

Since air is optically rarer than water, the ray of light bends away from the normal at the point of incidence when moving from water to air while it bends towards the normal while moving from air to water. The normal at any point of a spherical bubble will pass through the center of the bubble. It is clearly visible that the air bubble acts as a diverging lens (concave lens) in water.

Answer 2

“Air bubbles in water behave like a concave lens in water because air has less refractive index than water.”

“A ray of light is bent towards the perpendicular when entering a higher index medium like water and away from the perpendicular when exiting a higher index medium.”

In a Concave bubble, “a ray passing through the centre of the bubble will not be refracted at all at either transition.  A ray perpendicular to the plane of the lens formed by the bubble will be refracted away from the centre of the bubble.  This effect is one of divergence”