What is critical angle and total internal reflection?

With the help of a neat labelled diagram, explain partial reflection, critical angle and total internal reflection.

A ray of light enters in denser medium from rarer medium. Speed of light in rarer medium is double than that in denser medium, what is the critical angle for total internal reflection ?

Draw a labelled ray diagram to illustrate (a) critical angle (b) total internal reflection for a ray of light moving from one medium to another.

Define critical angle for total internal reflection.

Define critical angle. Explain total internal reflection using a neat diagram.

A ray of light strikes a glass plate at an angle of incidence 57^(@) . If the reflected and refracted rays are perpendicular to eachother, calculate critical angle for total internal reflection at glass air interface.

What is total internal reflection?