Question

A room is illuminated by an extended source. The illuminance at a particular portion of a wall can be increased by
(a) moving the source (b) rotating the source
(c) bringing some mirrors in proper positions
(d) changing the colour of the source.

Answer 1

Answer:

Option A is the answer. ...

Answer 2

A room is illuminated by an extended source. The illuminance at a particular portion of a wall can be increased by

(a) moving the source

(b) rotating the source

(c) bringing some mirrors in proper positions

(d) changing the colour of the source

Therefore all the options are correct

Explanation:

At a particular potion of the wall, the illuminance can be increased by rotating the source, moving the source, changing the source colour and bringing some mirrors in proper positions.  

(a) When the source is moved to the middle, it will illuminate the surface. So, depending on the illuminance there will be the distance from the source.

(b) when the source is rotation, there will be an effect as the illuminance is dependent on the angle made by the surface normal.

(c) When mirrors are brought to the proper position, the illuminance will be increased at the wall’s particular portion by assembling light and directing them at one point.

(d) Some colours are sensed by our eyes as bright and some hues as dull, choosing the colours near yellow result in making the wall brighter.