Question

how does a concave mirror , used as a reflector in a torch , produce a beam of light in the forward direction

Answer 1

So, in order to ensure that the other rays are also made useful, a concave / parabolic mirror is placed behind the bulb. The bulb is kept at the focus of the mirror) so that the rays going in the backward are reflected by the mirror towards the forward direction, parallel to the axis of the mirror