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ICSE Class 10 Physics Question 14 of 27

Solved Sample Paper 4 — Question 1

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Question 4(i)

A boy uses monochromatic green light to find the refractive index. When a ray of monochromatic green light enters in a liquid medium from air medium as shown in the figure given below, the angle 1 is 45° and angle 2 is 30°.

A boy uses monochromatic green light to find the refractive index. When a ray of monochromatic green light enters in a liquid medium from air medium as shown in the figure given below, the angle 1 is 45° and angle 2 is 30°. Determine the refractive index of the liquid. Represent in the diagram showing the path of the ray after it strikes the mirror and re-enters air. Mark in the diagram wherever necessary. Draw the diagram again, if plane mirror becomes normal to the refracted ray inside the liquid. Name the principle used. Physics Sample Paper Solved ICSE Class 10.

(a) Determine the refractive index of the liquid.

(b) Represent in the diagram showing the path of the ray after it strikes the mirror and re-enters air. Mark in the diagram wherever necessary.

(c) Draw the diagram again, if plane mirror becomes normal to the refracted ray inside the liquid. Name the principle used.

Answer

(a) Refractive index of the liquid is given by Snell's law and is shown as below,

airμliquid = sin isin r\dfrac{\text{sin i}}{\text{sin r}}

airμliquid = sin 45°sin 30°\dfrac{\text{sin 45}\degree}{\text{sin 30}\degree}

=1212=22=2=1.414= \dfrac{\dfrac{1}{\sqrt{2}}}{\dfrac{1}{2}} \\[1em] = \dfrac{2}{\sqrt{2}} \\[1em] = \sqrt{2} \\[1em] = 1.414 \\[1em]

Hence, the refractive index of the lens is 1.4

(b) Below labelled diagram shows the path of the ray after it strikes the mirror and re-enters in air:

A ray of green light enters a liquid from air, as shown in the figure. The angle 1 is 45° and angle 2 is 30°. Find the refractive index of liquid. Show in the diagram the path of the ray after it strikes the mirror and re-enters in air. Mark in the diagram the angles wherever necessary. Redraw the diagram if plane mirror becomes normal to the refracted ray inside the liquid. State the principle used. Refraction of light at plane surfaces, Concise Physics Class 10 Solutions.

(c) Below labelled diagram shows the path of the ray when it strikes the plane mirror normally inside the liquid:

A ray of green light enters a liquid from air, as shown in the figure. The angle 1 is 45° and angle 2 is 30°. Find the refractive index of liquid. Show in the diagram the path of the ray after it strikes the mirror and re-enters in air. Mark in the diagram the angles wherever necessary. Redraw the diagram if plane mirror becomes normal to the refracted ray inside the liquid. State the principle used. Refraction of light at plane surfaces, Concise Physics Class 10 Solutions.

The principle of reversibility is used.