What is critical angle?

Answer the following questions If the refractive index of a rarer medium with respect to a denser medium is 0.5 what is the critical angle ?

What is critical velocity ?

What is "critical temperature"?

What is critical velocity? Obtain an expression for critical velocity of an orbiting satellite. On what factors does it depend?

Define critical velocity and derive an expression for the same. OR What is critical velocity? Derive an expression for critical velocity of a satellite orbiting at a certain height. Also discuss the formula when satellite is very close to the earth's surface.

A ray of light travelling in water is incident on its open surface in air. The angle of incidence is theta^@ , which is less than the critical angle. Then there will be

A ray of light travelling in water is incident on its surface open to air. The angle of incidence is theta , which is less than the critical angle. Then there will be

A green light is incident from the water to the air - water interface at the critical angle (theta) . Select the correct statement.

Assertion: in optical fibre, the diameter of the core is kept small. Reason: This smaller diameter fo the fibre should have incident angle more than the critical angle required for total internal reflection.

A ray of monochromatic light is incident on one refracting face of a prism of refracting angle 75^(@) . It passes through the prism and is incident on the other face at the critical angle If the refracive index of the material of prism is sqrt(2) , the angle of incidence on the first face o the prism is