Physics
The refracting angle of prism is 60° and the angle of deviation is 30°. In the position of minimum deviation, the angle of incidence i1 and the angle of emergence i2 are :
- i1 = 45°, i2 = 30°
- i1 = 30°, i2 = 45°
- i1 = 45°, i2 = 45°
- i1 = 30°, i2 = 30°
Refraction Plane Surfaces
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Answer
i1 = 45°, i2 = 45°
Reason — Given
- A = 60°
- δ = 30°
In the position of minimum deviation for a prism, the path of light inside the prism is symmetrical. Therefore, the angle of incidence equals the angle of emergence, i.e., i1 = i2.
The relation between the angle of deviation δ, refracting angle A, and angle of incidence i is given by,
On putting values,
Thus, i1 = i2 = 45°
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Related Questions
Mention the incorrect statement:
- The angle of deviation produced by a prism depends on the colour or wavelength of the light used.
- The angle of incidence also affects the angle of deviation produced by the prism.
- In a prism as well as a parallel sided glass slab the emergent ray is parallel to the incident ray with a lateral displacement.
- 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 :
- 45°
- 90°
- 60°
- 0°
Assertion (A): If the angles of the base of a prism are equal, then in the position of minimum deviation, the refracted ray will pass parallely to the base of the prism.
Reason (R): For minimum deviation, angle of incidence is equal to the angle of emergence.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true and R is not the correct explanation of A.
- assertion is false but reason is true.
- assertion is true but reason is false.
Complete the following sentence:
Angle of deviation is the angle which the …………… ray makes with the direction of …………… ray.