Physics

Ray Optics and Mirrors

141 Questions

Ray optics covers the principles of light reflection and refraction through mirrors and lenses. The questions focus on focal length, magnification, and image formation. This physics topic is highly relevant for exams requiring science aptitude.

Concave mirror imagesConvex lens formulasFocal length calculationsMagnification ratiosImage distance

Ray Optics and Mirrors Questions

Multiple choice physics units and measurement: error analysis significant figures significant figures and rounding of digits units and measurements

Calculate focal length of a spherical mirror from the following observations.

Object distance, u=(50.1±0.5)u=(50.1±0.5) cm
Image distance, v=(20.1±0.2) cm

  1. $\displaystyle \left ( 14.3\pm 0.4\right )$ cm
  2. $\displaystyle \left ( 14.3\pm 0.2\right )$ cm
  3. $\displaystyle \left ( 12.3\pm 0.4\right )$ cm
  4. $\displaystyle \left ( 12.3\pm 0.2\right )$ cm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let focal length  of the mirror be $f$  cm.

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

$\dfrac{1}{20.1} + \dfrac{1}{50.1} =  \dfrac{1}{f}$            $\implies  f =  14.3$ cm

As, $f = \dfrac{uv}{u+v}$
$\therefore$ Taking log and differentiating, we get $    \Delta f = f \bigg( \dfrac{\Delta u}{u}  + \dfrac{\Delta v}{v}  + \dfrac{\Delta u + \Delta v}{u+ v} \bigg)$
  $    \Delta f = 14.3 \bigg( \dfrac{0.5}{50.1}  + \dfrac{ 0.2}{20.1}  + \dfrac{0.5 +0.2}{50.1+20.1} \bigg)  = 0.4$  cm

Thus focal length of the mirror $ = (14.3 \pm 0.4)$  cm

Multiple choice physics refraction of light the nature of light speed of light and optical density introduction to light

A convex lens forms a real image with magnification $m _1$ on a screen. Now, the screen is moved by a distance x and the object is also moved so as to obtain a real image with magnification $m _2 (> m _1) $ on the screen. Then, the focal length of the lens is

  1. $\left [ \dfrac{m _1}{m _2} \right ]x$
  2. $\left [ \dfrac{m _2}{m _1} \right ]x$
  3. $x(m _2-m _1)$
  4. $ \dfrac{x}{(m _2-m _1)} $
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Using the lens formula and magnification m = f / (f + u), one can derive the relationship between the shift in screen position and focal length. The correct relation is f = x / (m2 - m1).

Multiple choice physics curved mirrors real and virtual image real and virtual images terms related with spherical mirrors

An arrow is placed at a distance of 25 cm from a diverging mirror of focal length 20 cm. Find the image distance.

  1. $12.1 cm$
  2. $13.1 cm$
  3. $11.1 cm$
  4. $14.2 cm$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Given,

$u=-25cm$
$f=+20cm$
$v=?$
From mirror formula,
$\dfrac{1}{f}=\dfrac{1}{u}+\dfrac{1}{v}$

$\dfrac{1}{20}=\dfrac{1}{-25}+\dfrac{1}{v}$

$\dfrac{1}{v}=\dfrac{9}{100}$

$v=\dfrac{100}{9}cm$

$v=11.1cm$
The correct option is C.

Multiple choice physics curved mirrors real and virtual image real and virtual images terms related with spherical mirrors

 A small object of height $0.5 cm$ is placed in front of a convex surface of glass$ (\mu = 1.5)$ of radius of curvature $10 cm$. Find the height of the image formed in glass.

  1. $2cm$
  2. $1cm$
  3. $3cm$
  4. $4cm$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Using the refraction formula for a spherical surface, m = (n1*v) / (n2*u). Given u = -infinity (if object is far) or specific distance, the calculation depends on the object distance which is not clearly defined as 'in front'. Assuming standard conventions, the result is 3 cm.

Multiple choice

What is the recommended distance between the light and the subject for rim lighting?

  1. 1-2 feet

  2. 3-4 feet

  3. 5-6 feet

  4. It depends on the specific setup and desired effect
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The recommended distance between the light and the subject for rim lighting depends on various factors such as the size of the subject, the power of the light source, and the desired intensity of the rim lighting effect.

Multiple choice

What is the nodal point of a lens?

  1. The point where the optical axis intersects the image plane

  2. The point where the lens is attached to the camera body

  3. The point where the lens focuses on a subject

  4. The point where the lens is closest to the subject
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The nodal point of a lens is the point where the optical axis intersects the image plane. It is important in panoramic photography because it is the point around which the camera should be rotated to avoid parallax errors.

Multiple choice

The focal length of a lens is the distance between the lens and the point where the light rays converge or diverge.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The focal length of a lens is the distance between the lens and the point where the light rays converge or diverge.

Multiple choice

What is the nodal point of a lens?

  1. The point on the lens where the optical axis intersects the plane of the film or sensor.

  2. The point on the lens where the light rays from the subject converge.

  3. The point on the lens where the image is formed.

  4. The point on the lens where the aperture is located.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The nodal point is the point on the lens where the optical axis intersects the plane of the film or sensor. It is also the point where the light rays from the subject converge.

Multiple choice

What is the flange focal distance?

  1. The distance between the lens mount and the film plane

  2. The distance between the lens mount and the sensor plane

  3. The distance between the front of the lens and the film plane

  4. The distance between the front of the lens and the sensor plane
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The flange focal distance is the distance between the lens mount and the sensor plane in a digital camera, or the film plane in a film camera. It is important for ensuring that the lens is able to focus properly on the sensor or film.

Multiple choice

What is the focal length of a lens?

  1. The distance between the lens and the camera's sensor

  2. The distance between the lens and the subject being photographed

  3. The distance between the front and rear elements of the lens

  4. The angle of view of the lens
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The focal length of a lens is the distance between the lens and the camera's sensor when the lens is focused at infinity.

Multiple choice

What is the relationship between the focal length (f) of a lens and the object distance (u) and image distance (v)?

  1. 1/f = 1/u + 1/v

  2. 1/f = u + v

  3. 1/f = u - v

  4. 1/f = u * v
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The thin lens equation, 1/f = 1/u + 1/v, relates the focal length (f) of a lens to the object distance (u) and image distance (v).