Mirage

Q.

If the critical angle for TIR from medium to vacuum is ${30}^{\circ },$ the velocity of light in medium is:

1. $3\times {10}^{8}m/s$

2. $1.5\times {10}^{8}m/s$

3. $6\times {10}^{8}m/s$

4. $\sqrt{3}\times {10}^{8}m/s$

Q. The amplitude of electric filed if a laser beam of 500 W is concentrated on a cross sectional area of 10^-10 m^2 is

Q. The beautiful natural phenomenon of the rainbow is a combination of which of the following different phenomena?

1. Refraction, reflection
2. Dispersion, refraction
3. Refraction, dispersion, reflection
4. Reflection, dispersion

Q. Which of the following is a possible application of fibre optics?

1. Endoscopy
2. High speed internet
3. Radio, TV and Telephone signal
4. All of above

Q. What is dual nature of light?

Q.

Periscope works on the principle of

Q. 13. Find the angle at which a ray must be incident ona glass prism of refracting angle 75^° such thatemergent ray comes out parallel to the facethrough which it comes out. (This is known asthe &grazing emergence)ng= 2)

Q.

Diamond sparkle because of

1. Refraction

2. Reflection

3. Total Internal Reflection

4. Total Internal Refraction

Q. The Refractive index $\mu$ atmosphere around a planet varies with altitude h according to equation$\mu ={\mu }_0-kh$. Here ${\mu }_0$ und $k$ are positive constants. Denoting radius of planet by $R$, altitude at which a point flash of light spreads around the planet in a spherical layer is $\frac{n({\mu }_0-kR)}{k}$, then value of n is (Write upto two digits after the decimal point.)

Q. How may times total internal reflection occurs in the drop for formation of primary and secondary rainbows?

Q.

The formation of mirage is a consequence of :

1. Varying R.I & TIR

2. Varying R.I

3. TIR

4. None of them

Q. Conditions for internal reflection is:

1. Light must travel from rare to denser medium
2. The angle of incidence should be greater than the critical angle for the given pair of media
3. Both
4. None

Q. Two lamps of 8 CP and 32 CP are placed 99 cm apart . Where should a screen be put on the line joining them so that it is equally illuminated

Q. 5. In Y.D.S.E., the slits are 0.2 cm apart & are illuminated by yellow light ( 600 nm). What would be the fringe width on a screen placed 1 m from the plane of the slits if the whole systemis immersed in water of index 4/3 (1) 0.225 mm(2) 2.25(2)2.25 mm

Q. A diver in a swimming pool wants to signal his distress to a person lying on the edge of the pool by flashing his waterproof flash light:

1. He must direct the beam vertically upwards
2. He has to direct the beam horizontally
3. He has to direct the beam at an angle to the vertical which is slightly less than the critical angle of incidence
4. He has to direct the beam at an angle to the vertical which is slightly more than the critical angle of incidence for total internal reflection

Q. The light reflected back into the denser medium when a ray of light passes from a denser to a rarer medium, is said to be ......

1. Totally relfected
2. Internally reflected
3. Totally refracted
4. Internally refracted

Q. P-112(QB) Q-22 A luminous object is placed at a depth of h through u refractive index. Show that the radius of the circular ground of the cone through which light will pass is r=h/√(u²-1)

Q. Assertion :The diamond shines due to multiple total internal reflections. Reason: The critical angle for diamond is 24.4${}^o$.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. Assertion :The images formed by total internal reflections are much brighter than those formed by mirrors or lenses Reason: There is no loss of intensity in total internal reflection.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Q. The refractive index of water with respect to air is $1.33$. Calculate the critical angle for water air interface

1. ${76}^{\circ }{5}^1$
2. ${26}^{\circ }$
3. ${22}^{\circ }{6}^1$
4. ${48}^{\circ }{45}^1$

Q.

Choose the wrong statement(s)

1. The formation of an image is always due to the reflection.

2. Real images can not be formed due to the reflection of light.

3. The formation of a real image is always due to the refraction of the light rays.

4. All of the above.

Q. Which of the following is a consequence of total internal reflection?

1. Optical fibre
2. Mirage
3. Looming
4. All

Q. In a lake 2m deep, a measuring post of height 3m is fixed vertically. For an angle of incidence of 30° of Sun’s radiations, find the length of the shadow of the post at the bottom surface?(μw = 4/3)

Q. Mirage is found due to

1. Refraction of light
2. All
3. Reflection of light
4. Total internal reflection

Q. Multiple internal reflection is seen in

1. Refraction of light
2. Reflection of light
3. Total internal reflection
4. All

Q. Assertion (A) : Formation of mirages in hot deserts is a phenomena of total internal reflection.
Reason (R) : Air close to the land is hotter than the air far from the land in a hot desert.

1. a) Statement A is correct R is wrong
2. b) Statement A is correct R is right
3. d) Statement A and R both are correct and R is explaining A
   
4. c) Statement A and R both are correct but R is not explaining A

Q. The amplitude of electric filed if a laser beam of 500 W is concentrated on a cross sectional area of 10^-10 m^2 is

Q. What is polarised light?

Q. A container contains water up to a height of $20cm$ and there is a point source at the centre of the bottom of the container. A rubber ring of radius $r$ floats centrally on the water. The ceiling of the room is $2.0m$ above the water surface. (a) Find the radius of the shadow of the ring formed on the ceiling if $r=15cm$. (b) Find the maximum value $r$ for which the shadow of the ring is formed on the ceiling. Refrective index of water $=4/3$.

Q. Prismatic periscopes use the principle of :

1. refraction
2. reflection
3. transmission
4. total internal reflection