Advertisements
Advertisements
प्रश्न
Answer the following question.
Define the critical angle of incidence and obtain an expression for it.
उत्तर
- The critical angle for a pair of refracting media can be defined as that angle of incidence in the denser medium for which the angle of refraction in the rarer medium is 90°.
- Let n be the relative refractive index of a denser medium with respect to the rarer.
- Then, according to Snell’s law,
n = `"n"_"denser"/"n"_"rarer"=(sin"r")/(sin"i"_"c")=(sin90°)/(sin"i"_"c")`
∴ sin (ic) = `1/"n"`
APPEARS IN
संबंधित प्रश्न
A ray of light travels from water to air as shown in the diagram given below :
1) Copy the diagram and complete the path of the way. Given the critical angle for water is 48°.
2) State the condition so that internal reflection occurs in the above diagram.
Which colour of light has a higher critical angle? Red light or green light.
What do you understand by the deviation produced by a prism? Why is it caused?
Prove the statement.
A rainbow is the combined effect of the refraction, dispersion, and total internal reflection of light.
Define critical angle for a given medium.
Plot a graph between
Angle of incidence versus angle of reflection,
How does a ray of light bend when it travels from rarer to denser medium
Write down the relationship between the critical angle and the refractive index of the medium.
Complete the following diagram to show the path of the ray of a single colour in the diagram as if enters in and emerges out of the prism. Mark the angles wherever necessary. (Critical angle for glass = 42°).
Choose the correct option.
Select the WRONG statement.
Choose the correct option.
Angles of deviation for extreme colours are given for different prisms. Select the one having maximum dispersive power of its material.
Answer the following question.
Explain ‘mirage’ as an illustration of refraction.
Answer the following question.
What are the advantages of optical fibre communication over electronic communication?
Observe the given figure and write appropriate phenomenon of light in the box.
A green light is incident from the water to the air-water interface at the critical angle `(theta)`. Select the correct statement
Which one of the following is NOT the correct formula for refractive index of glass w.r.t. air (aμg) (i = angle of incidence, r = angle of refraction)
A particle is projected such that the horizontal range and vertical height are equal. Then the angle of projection is :
Define the critical angle.
A green light is incident from the water to the air-water interface at the critical angle (θ). Select the correct statement.
A rectangular block of glass ABCD has a refractive index 1.6. A pin is placed midway on the face AB (Figure). When observed from the face AD, the pin shall ______.
- appear to be near A.
- appear to be near D.
- appear to be at the centre of AD.
- not be seen at all.
State the condition under which total internal reflection occurs. Give the mathematical expression for total internal reflection.
A ray of light passes through a prism of refractive index `sqrt2` as shown in the figure. Find:
- The angle of incidence (∠r2) at face AC.
- The angle of minimum deviation for this prism.
Which of the following is used in optical fibres?
A given ray of light suffers minimum deviation in an equilateral prism P. Additional prism Q and R of identical shape and of the same material as P are now added as shown in the figure. The ray will now suffer ______.
The angle made by incident ray of light with normal of the reflecting surface is called ______.
Find the value of θ in the given figure.
Name any two phenomena which take place in the formation of a rainbow.
