Question

Which of the following graph represents the correct variation of angle of incidence

(i) and angle of deviation (δ)?

a. Figure A

b. Figure B

c. Both Figure C And

d. Only Figure D​

Answer 1

Answer:

By comparing graph with standard plot, we get δ=30°,i

1

=15°,i

2

=60°

as δ=i

1

+i

2

−A

∴A=i

1

+i

2

−δ

=15°+60°−30°=45°

Answer 2

Answer:

option A is the correct answer.

Explanation:

In a prism, the angle of deviation(δ)gets less as the angle of incidence gets bigger up to a certain degree.

• Experimental research has shown that as the angle of incidence is increased initially, the angle of deviation first falls, reaches a minimal value, and then increases once again.
• When the angle of incidence at the first surface and the angle of emergence at the second surface are identical, a prism is said to be in the minimal deviation position. When this occurs, the rays inside the prism move parallel to the base. We refer to their movement as symmetrical.
• The refracting angles at the two surfaces are identical when the deviation is at its lowest value. If the prism is an isosceles triangular prism, the ray within should only be parallel to the base.

By comparing the graph with the standard plot, we get δ=30°, i

1

=15°, i

2

=60°

as δ=i

1

+i

2

−A

∴A=i

1

+i

2

−δ

=15°+60°−30°=45°