Re: how does the intensity of the light affect the darkness of the shadow?

The intensity of the light doesn't affect the shadow, it's the size and 
distance of the light source that makes the shadow fuzzy or sharp.
If you fix the light at one end of the room and move the ball you will 
see that the sharpness of the shadow increases as you get farther from 
the light.
This is because from a point source the light is all coming from one 
place. If the source is bigger the light is coming from the whole area of 
the source this causes a penumbra to form which is the fuzzyness you see 
(see picture).

The darkness of the umbra will be less if there is a lot of ambient light 
in the room which may be coming from the torch.  To eliminate this in your 
experiment you could turn off all the lights in the room and use a narrow 
beam torch so that less stray rays affect your shadow.

Hope this helps
J. Armour