Luminosity is measured in $\mathrm{J} {\mathrm{s}}^{-1}$.

The formula for the angle of deviation in the case of a plane mirror is $\delta =$_____${}^{\circ }-\left(2i+g\right)$ where $i$ is the angle of incidence and $g$ is the glancing angle.

The light from a flashlight is an example of a beam that is _____.

Calculate how many lumens make $62.8 \mathrm{candle} \mathrm{power}$.

In which of the given arrangement, the flame of a candle can be seen clearly through the other end of the pipe?

A beam of light consists of-