Fill in the blanks below:
 
A student sitting at the back of the classroom cannot read clearly the letters written on the blackboard. What advice will a doctor give to her? Draw ray diagram for the correction of this defect.
 
The student is suffering from .
 
This defect is also known as .
 
In this defect, a person can see clearly.
 
Doctor advises her to use a  of appropriate power to correct this defect.
 
Select the ray diagram for the correction of this defect: