Refractive index of a glass slab and prism deviation — NEET & JEE Questions

Question 1 · difficulty L1 · recall

For a plane glass slab viewed normally from air, refractive index can be estimated as

• A. apparent depth/real depth
• B. real depth + apparent depth
• C. real depth/apparent depth
• D. real depth × apparent depth

Question 2 · difficulty L1 · understanding

A glass slab makes an object beneath it appear

• A. farther away
• B. at the same depth for all refractive indices
• C. inverted by reflection only
• D. closer to the observer than its real position

Question 3 · difficulty L2 · understanding

For a prism, minimum deviation occurs when

• A. the ray path through the prism is symmetric
• B. incidence angle is always zero
• C. the ray reflects internally at both faces
• D. the prism angle is zero

Question 4 · difficulty L2 · application

At minimum deviation, prism refractive index is

• A. n=sin(A/2)/sin[(A+δm)/2]
• B. n=sin[(A+δm)/2]/sin(A/2)
• C. n=A/δm
• D. n=δm/A

Question 5 · difficulty L2 · understanding

For an object viewed normally through a plane glass slab from air, refractive index is approximately

• A. real depth divided by apparent depth
• B. apparent depth divided by real depth
• C. real depth plus apparent depth
• D. real depth multiplied by apparent depth

Question 6 · difficulty L3 · application

A glass slab has real thickness 6.0 cm and apparent thickness 4.0 cm when viewed normally. Its refractive index is

• A. 0.67
• B. 2.0
• C. 1.5
• D. 10

Question 7 · difficulty L3 · application

Why should pins be kept well separated in a prism ray-tracing experiment?

• A. It changes the prism angle
• B. It removes refraction
• C. It makes all deviation zero
• D. Greater separation improves the accuracy of aligning their straight-line direction

Question 8 · difficulty L3 · application

A mark lies 6.0 cm below the top surface of a glass slab but appears 4.0 cm deep when viewed normally from air. What is the refractive index of the glass?

• A. 0.67
• B. 1.0
• C. 1.5
• D. 2.5

Question 9 · difficulty L3 · application

A prism has angle $A=60^\circ$ and minimum deviation $D_m=40^\circ$. Which expression gives its refractive index in air?

• A. $\frac{\sin50^\circ}{\sin30^\circ}$
• B. $\frac{\sin30^\circ}{\sin50^\circ}$
• C. $\frac{\sin40^\circ}{\sin60^\circ}$
• D. $\frac{\sin20^\circ}{\sin30^\circ}$

Question 10 · difficulty L4 · analysis

A prism's deviation is measured for several incidence angles. The deviation-versus-incidence graph typically has

• A. a minimum
• B. only a straight increasing line
• C. no dependence on incidence
• D. a maximum at the symmetric path