The angle of deviation becomes minimum when:

1. i₁ = r₁
2. i₁ = r₂
3. i₁ = i₂
4. r₂ = i₂

Mention the incorrect statement:

1. The angle of deviation produced by a prism depends on the colour or wavelength of the light used.
2. The angle of incidence also affects the angle of deviation produced by the prism.
3. In a prism as well as a parallel sided glass slab the emergent ray is parallel to the incident ray with a lateral displacement.
4. The angle of deviation of prism is also affected by the material of the prism.

A ray of light is incident normally on the face of an equilateral glass prism. The angle of refraction from the first face of prism is :

1. 45°
2. 90°
3. 60°
4. 0°