# Variation of acceleration due to gravity with depth. A doubt.

Rajkumar asks: “accelaration due to gravity decrease on depth of earth with the relation of g’=g(1-2h/R). but with relation of g=GM/(R*R)  g increase. Answer: When the object is on the surface or above it, the entire mass of the earth attracts it. But when it is inside, the net attraction towards CENTRE is provided only by the mass of [...]

# Some Questions from Electrostatics posted by visitors

An infinite no. of charges each equal to 4 micro coulomb are place along the x-axis at x=1m,2m,4m and so on.find the electric field at the origin due to given sets of charges. What is meant by a cavity and what is the electric field on the circumference of a cavity whose centre is at … Continue reading Some Questions from Electrostatics posted by visitors

# Why the ray of light passing through the centre of curvature of a concave mirror behave as normal while it doesn’t behave as normal when it passes through other points on the principal axis?

Remember that a concave mirror forms part of a hollow sphere. Any line joining the centre of the sphere (the centre of curvature of the mirror) and any point on the mirror will be normal to the reflecting surface of the mirror. Therefore A ray of light passing through the principal axis will be normal … Continue reading Why the ray of light passing through the centre of curvature of a concave mirror behave as normal while it doesn’t behave as normal when it passes through other points on the principal axis?