An extended source illuminates a room. The illuminance at a...

Illuminance at a surface is the luminous flux incident per unit area. It depends on the distance from the source, the orientation of the source (for an extended source), and the total flux reaching the surface.

Shifting the source closer to the wall decreases the distance, thereby increasing the illuminance.

Rotating an extended source can change the luminous intensity directed towards the specific section of the wall, which can enhance the illuminance if oriented optimally.

Decreasing the luminous flux of the source will reduce the illuminance.

Placing mirrors in suitable locations can direct additional reflected light onto the specific section of the wall, thereby increasing the total luminous flux incident on it and enhancing the illuminance.