1. Power of the light source: The more powerful the light source, the greater the intensity of light it will produce.

2. Distance from the light source: The intensity of light decreases as the square of the distance from the light source. This means that if you move twice as far away from a light source, the intensity of light will be four times weaker.

3. Absorption and scattering of light: The intensity of light can be reduced by absorption and scattering of light by particles in the atmosphere, such as dust, water vapor, and smoke.

4. Reflection of light: The intensity of light can be increased by reflection of light from surfaces, such as walls, ceilings, and floors.

5. Focusing of light: The intensity of light can be increased by focusing it with lenses or mirrors.