Given: Focal Length (f) = 2m

Points to Remember: 

• The images formed can be real as well as virtual by a concave lens.
• As per the sign convention, the concave len's focal length is always negative.
• The straight beam of light from the source is diverted by the concave lens to the virtual and upright image.

Power of the lens:

P = 1/f 

P = 1/(-2)

P = -(0.5)D