OPTICS

Answer :

no. of image formed = n = (360 / θ) ‑‑‑‑‑‑‑‑‑ if (360 / θ) is odd

                                                    n = (360 / θ) – 1 ‑‑‑‑‑‑‑‑ if (360 / θ) is even

                   given n = 5 hence θ = (360 / n)         OR    θ = [(360) / (n + 1)]

                                      ∴       θ = (360 / 5)         OR    θ = (360 / 6)

                                                θ = 72°        OR    θ = 60°

                                      ∴       θ = 72°.      

Answer :

If glass rod is immersed in a liquid of a same refractive index then it will disappear. Objects are visible when they reflect the light, when object is immersed in a liquid having refractive index different than that of object, then some of light is ferreted and some is reflected back. So if refractive index is same then light will never reflect or refract at the interface & object will appear to disappear.

Answer :

         n₄₁ × n₁₂ × n₂₁        = (v₁ / v₄) × (v₂ / v₁) × (v₁ / v₂)

                                                = (v₁ / v₄)

                                                = n₄₁

                                                = (1 / n₁₄)   

Answer :

Plane mirror produce magnification of +1. As the image obtained is erect and it is of same size as the object.  

Answer :

height of object = h₀ = √(h₁h₂)

                             here   h₁ = 16 cm

                                      h₂ = 4 cm

                             hence h₀ = √(16 × 4) = 8 cm