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

Options

A. only a reflected ray and no refracted ray
B. only a refracted ray and no reflected ray
C. a reflected ray and a refracted ray and the angle between them would be less than `(180^(@) - 2theta)`
D. a reflected ray and a refracted ray and the angle between them would be greater than `(180^(@) - 2theta)`

Answer

C

Explanation

Angle of incidence is less than critical and hence light will be refracted into air for sure but there will also partial reflection at the interface and hence reflected and refracted rays both will be present as shown in diagram.

From figure we can see that angle between reflected and refracted can be written as follows :
`phi = 180^@ - (theta +r)`
`implies r = 180^@ - phi - theta`
Since light is travelling from denser to rarer medium hence ` r gt theta`
` = 180^@ - f - theta gt theta `
`implies f lt 180^@ - 2theta`