A thin lens, made of glass of refractive index `3//2,` produces a real and magnified image of an object in air. If the whole system, maintaing the same distance between the object and the lens, is immersed in water `(RI=4//3),` then the image formed will be

Options

A. real and magnified
B. virtual and magnified
C. virtual and magnified
D. virtual and diminished

Answer

C

Explanation

`(1)/(f)=((3)/(2)-1)((1)/(R_1)-(1)/(R_2))`
`(1)/(f_(omega))=((3//2)/(4//3)-1)((1)/(R_1)-(1)/(R_2))`
`(f_(omega))/(f)=4impliesf_(omega)=4f`
Case I: `(1)/(v_1)-(1)/(-x)=(1)/(f)implies(1)/(v_1)=(1)/(f)-(1)/(x)=(x-f)/(fx)`
Since for real magnified image `f lt xxgt2f`
`v_(1)=(fx)/(x-f)=+ve`.
`m_1=(v_1)/(-x)=-(fx)/((x-f))gt(-1)`
Case II: `(1)/(v_2)-(1)/(-x)=(1)/(4f)implies(1)/(v_2)=(1)/(4f)-(1)/(x)=(x-4f)/(4fx)`
`v_2=(4fx)/(x-4f)=-ve`
`m_2=(v_2)/(-x)=(4fx)/(x-4f)=(f)/((x)/(4)-f)=+ve`
`|m_2|gt|m_1|`, virtual and magnified