Answer the following question.
 
A student uses spectacles of focal length \(– 2·5\ m\).

(a) Name the defect of vision he is suffering from.

(b) Which lens is used for the correction of this defect ?

(c) List two main causes of developing this defect.

(d) Compute the power of this lens.
 
(a). The defect of vision he is suffering from is .
 
(b) A can be used to correct this flaw.
 
(c). The of the eyeball causes this defect. The distance between the eye lens and the retina is , or the focal length of the eye lens is
 
(d) The power of the lens is .