Which of the following does not depend on the total internal reflecti…

The correct answer is Option (4) → Terrestrial Telescope

Total internal reflection occurs when light going from a denser to a rarer medium meets the boundary at an angle greater than the critical angle. Each option is checked for this.

Option (1) Mirage — Uses total internal reflection. Light from a distant object bends through the hot, rarer air layers near the ground and is finally totally reflected upwards, giving an inverted image.

Option (2) Endoscopy — Uses total internal reflection. The endoscope carries light through optical fibres, in which light is totally reflected again and again at the walls.

Option (3) Prism binoculars — Uses total internal reflection. Right-angled (\( 45^\circ \)) prisms inside the binoculars turn the light by total internal reflection and erect the image.

Option (4) Terrestrial Telescope — Does not use total internal reflection. A terrestrial telescope erects the image with an extra erecting lens between the objective and the eyepiece; it works only by refraction through lenses.

NCERT (2026-27):
Summary – “… For i > i_c, total internal reflection occurs. Multiple internal reflections in diamond (i_c ≅ 24.4°), totally reflecting prisms and mirage, are some examples of total internal reflection. Optical fibres consist of glass fibres coated with a thin layer of material of lower refractive index. Light incident at an angle at one end comes out at the other, after multiple internal reflections, even if the fibre is bent.”