Tag: option c: imaging

Questions Related to option c: imaging

The relation among $u$, $v$ and $f$ for a mirror is:

  1. $f=\dfrac{uv }{u + v}$

  2. $v = \dfrac{fu}{u + f}$

  3. $u=\dfrac{ fv}{f + v}$

  4. all of these


Correct Option: A
Explanation:

As we know,


$\dfrac{1}{f}=\dfrac{1}{v}+\dfrac{1}{u}$

$\dfrac{1}{f}=\dfrac{u+v}{uv}$


${f}=\dfrac{uv}{u+v}$

hence,option A is correct.

In case of a virtual and erect image, the magnification created by the mirror is

  1. positive

  2. negative

  3. unity

  4. infinity


Correct Option: A
Explanation:

Magnifaction of a mirror is defined as
$m=\dfrac{size of image}{size of object}$
and since, in case of virtual and errect image, size of image and object both are positive  . Hence magnification created by mirror is positive.

The sum of the reciprocals of object distance and image distance is equal to the __________ of a mirror.

  1. focal length

  2. reciprocal of the focal length

  3. radius of curvature

  4. reciprocal of the radius of curvature


Correct Option: B
Explanation:

$\dfrac{1}{v} + \dfrac{1}{u}$ = $\dfrac{1}{f}$

Hence, it is (B)

In case of a real and inverted image, the magnification created by the mirror is

  1. positive

  2. negative

  3. unity

  4. infinity


Correct Option: B
Explanation:

Magnification of image created by mirror is defined as
$m=\dfrac{size of image}{size of object}$
and in case of inverted image. Size of image is negative whereas size of object is positive. Hence , magnification produced is negative and it can be unity when object is placed at center of curvature and infinity when object is at focus.

Light of different colours propagates through air :

  1. with velocity of air

  2. with different velocity

  3. with velocity of sound

  4. with equal velocity


Correct Option: D
Explanation:
  • The velocity of the light does not change in air it will be equal for all the colours
  • If there may some other medium like water etc velocity will be changed
  • But it remains equal in air
  • Hence the option D is the right answer

Which of the following is used in optical fibres?

  1. Total internal reflection

  2. Scattering

  3. Diffraction

  4. Refraction


Correct Option: A
Explanation:

In optical fibers total internal reflection property of light waves are used, so as to confine the light rays inside the fiber.

Optical fibres transmit light along its axis, by the process of :

  1. total internal reflection

  2. refraction

  3. interference

  4. diffraction


Correct Option: A
Explanation:

The side-wall of optical fibre provides total internal reflection of beam of light incident on it.

In an optical fibre during transmission of light

  1. Energy increases.

  2. Energy decreases.

  3. No loss of propagation of energy takes place.

  4. Light partially reflects and refracts.


Correct Option: C
Explanation:

Attenuation is a gradual loss int he intensity of any kind of flux through a medium .in telecommunication the attenuation affect the propagation of waves and signals. so during transmission of light through  an optical fiber optical and electrical attenuators cause the loss in transmission.

Which principle is the basis for the transmission of light through fiber optic cables even if the cable is bent?

  1. Photoelectric effect

  2. Uncertainty principle

  3. Light diffraction

  4. Light polarization

  5. Total internal reflection


Correct Option: E
Explanation:

Optical fibres are used to transmit light from one place to another along curved path so it does not matter even if the cable is bent.Optical fibre transmission is based on phenomenon of total internal reflection .We must remember that optical fibre does not bend light, instead light follows a zig-zag path.

A cutted diamond sparkles because of its:

  1. high refractive index

  2. hardness

  3. emission of light by the diamond

  4. absorption of light by the diamond


Correct Option: A
Explanation:

A cutted diamond sparkles because of its high refractive index. Because of high refractive index, the light suffers total internal reflections many times. that is why it sparkles.