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Multiple choice problems on prism prism ray optics and optical instruments optics physics

A ray of light is incident at an angle of $60^{\circ}$ on one face of a prism of angle $30^{\circ}$. The emergent ray of right makes an angle of $30^{\circ}$ with incident ray. The angle made by the emergent ray with second face of prism will be

  1. $0^{\circ}$

  2. $90^{\circ}$

  3. $45^{\circ}$

  4. $30^{\circ}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Using the prism formula for deviation, the angle of emergence can be calculated. Given the incident angle and prism angle, the geometry confirms the emergent ray is parallel to the second face or at a specific angle.

Multiple choice problems on prism prism ray optics and optical instruments optics physics

A right-angled prism is set to deviate a ray of light through $90^o$ . If the same prism is to be used for deviating through $180^o$ , the prism must be turned from the previous set position through the angle :

  1. $45^o$

  2. $90^o$

  3. $135^o$

  4. $180^o$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A right-angled prism deviates light by 90 degrees when light enters one leg and exits the hypotenuse. To achieve 180 degrees, the prism must be rotated to reflect the light back along its original path.

Multiple choice problems on prism prism ray optics and optical instruments optics physics

Two thin prisms are combined to form an achromatic combination.For prism I, $  A=4^{0}, \mu _{R}=1.35, \mu _{Y}=1.40, \mu _{\nu}=1.42 .  $ For prism II $  \mu _{R}=1.7, \mu _{\gamma}=1.8  $ and $  \mu _{R}=1.9 .  $ Find the prism angle of prism II and the net mean deviation.

  1. $ 0.44^{\circ} $

  2. $ 0.45^{\circ} $

  3. $ 0.48^{\circ} $

  4. $ 0.46^{\circ} $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Achromatic combinations require the dispersive powers to cancel out. Using the formula (omega1 * A1) + (omega2 * A2) = 0, we can solve for the unknown prism angle.

Multiple choice problems on prism prism ray optics and optical instruments optics physics

When light rays are incident on a prism at an angle of $45^o$, the minimum deviation is obtained. If the refractive index of the material of the prism is $\sqrt 3$, then the angle of prism will be

  1. $2 \times {\sin ^{ - 1}}\frac{1}{{\sqrt 6 }}$

  2. $45^o$

  3. $60^o$

  4. $90^o$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

At minimum deviation, the angle of incidence i = (A + delta_m) / 2. Given i = 45 and mu = sqrt(3), we use the prism formula mu = sin((A+delta_m)/2) / sin(A/2) to solve for A.

Multiple choice problems on prism prism ray optics and optical instruments optics physics

The angle of minimum deviation produced by an equilateral prism is $46^0$. The refractive index of material of the prism.

  1. 1.6

  2. 1.5

  3. 1.4

  4. 1.8
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For an equilateral prism, A = 60 degrees. Using the formula mu = sin((A + delta_m) / 2) / sin(A / 2) with delta_m = 46 degrees, we find mu = sin(53) / sin(30) = 0.8 / 0.5 = 1.6.

Multiple choice problems on prism prism ray optics and optical instruments optics physics

The dispersive powers of flint glass and crown glass are $0.053$  and $0.034 $and respectively and their mean refractive indices are $1.68 $ and $1.53$for white light. Calculate the angle of the flint prism required to form an achromatic combination with a crown glass of refracting angle $4^0$

  1. $2^0$

  2. $4^0$

  3. $5^0$

  4. $6^0$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For an achromatic combination, the condition is omega1 * A1 + omega2 * A2 = 0. Substituting the given dispersive powers and the angle of the crown glass prism allows solving for the flint glass prism angle.

Multiple choice problems on prism prism ray optics and optical instruments optics physics

The refractive index of a prism is 2. The prism can have a maximum refracting angle of

  1. $90^o$

  2. $60^o$

  3. $45^o$

  4. $30^o$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Critical angle of the prism such that it does not refract back into the prism from the emerging side $=\theta _c=sin^{-1}(\dfrac{1}{\mu})=sin^{-1}\dfrac{1}{2}=30^{\circ}$


The angles made by the ray inside the prism cannot be greater than $30^{\circ}$.


$A=r _1+r _2$

If $A>60^{\circ}$, the ray does not emerge from the prism. So maximum refracting angle can be $60^{\circ}$.

Multiple choice problems on prism prism ray optics and optical instruments optics physics

A ray of monochromatic light is incident on the refracting face of a prism (angle $75^o$). It passes through the prism and is incident on the other face at the critical angle. If the refractive index of the prism is $\sqrt 2$, then the angle of incidence on the first face of the prism is :

  1. $15^o$

  2. $30^o$

  3. $45^o$

  4. $60^o$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
As the ray on the other face is incident on critical angle $r^{'}=sin^{-1}\dfrac{1}{\mu}=sin^{-1}\dfrac{1}{\sqrt{2}}=45^o$

So the refracting angle on first surface $r=A-r^{'}=75^o-45^o=30^o$

Applying snell's law for first surface,

$\mu _{1}sin\alpha _{1}=\mu _{2}sin\alpha _{2}$ 

$1\times sin i=\sqrt{2}sin30^o$

$i=45^o$, hence option $C$ is correct. 
Multiple choice problems on prism prism ray optics and optical instruments optics physics

A beam of light consisting of red, green, and blue colors is incident on a right-angled prism. The refractive indices of the material of the prism for the above red, green, and blue wavelengths are 1.39, 1.44, and 1.47, respectively. The prism will

  1. separate part of the red color from the green and blue color

  2. separate part of the blue color from the red and green color

  3. separate all the three colors from one another

  4. not separate even partially any color from the other two colors
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The prism will separate part of the red color from the green and blue color as the refractive index are different hence they undergo different deviations
hence correct option is $A$.

Multiple choice problems on prism prism ray optics and optical instruments optics physics

A thin prism of angle $7^o$ made of glass of refractive index $1.5$ is combined with another prism made of glass of $\mu =1.75$ to produce dispersion without deviation. The angle of second prism is :

  1. $7^o$

  2. $4.67^o$

  3. $9^o$

  4. $5^o$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The condition for dispersion without deviation is (mu1 - 1) * A1 + (mu2 - 1) * A2 = 0. Using the given values, we solve for A2.