question_answer

A diverging lens of 10 cm focal length made of glass (\[\mu \]= 1.5) is immersed in water \[\left( \mu =\frac{4}{3} \right).\] The lens when immersed in water has a focal power:

A)  2.5 dioptre        

B)  - 2.5 dioptre     

C)         10 dioptre         

D)         4 dioptre