When seen in green light,the saffron and green portions of our National Flag will appear to be

Five lumen/watt is the luminous efficiency of a lamp and its luminous intensity is $35$ candela. The power of the lamp is.......$W$

If $\hat{n}_1$ is the unit vector along the incident ray,$\hat{n}_2$ is the unit vector along the normal,and $\hat{n}_3$ is the unit vector along the reflected ray,then which of the following must be true?

For a concave mirror, if a virtual image is formed, the graph between $m$ and $u$ is of the form:

Which of the following can form a diminished,virtual,and erect image of your face?

During a cloudy day,a primary and a secondary rainbow may be created,then the: