Physics

Light and Mirrors

458 Questions

Light and mirrors questions cover the principles of reflection, image formation, and mirror magnification. Concepts include the properties of plane mirrors, the uses of concave mirrors in solar devices, and the behavior of light rays. These fundamentals are essential general science topics in major competitive examinations.

Plane mirror propertiesConcave mirror applicationsMirror magnification formulaLight reflection lawsImage formation

Light and Mirrors Questions

Multiple choice physics light : reflection and refraction from plane surface introduction to light and mirror magic with mirrors image formation by plane mirror principle of reversibility of path of light refractive index

The reflective surface is given by y $=$ 2 sinx. The reflective surface is facing positive x-axis. What is the least values of co ordinate of the point where a ray parallel to positive x axis becomes parallel to positive y axis after reflection 2. 

  1. $\left ( \dfrac{\pi }{3},\sqrt{3} \right )$
  2. $\left ( \dfrac{\pi }{2},\sqrt{2} \right )$
  3. $\left ( \dfrac{\pi }{3},\sqrt{2} \right )$
  4. $\left ( \dfrac{\pi }{4},\sqrt{2} \right )$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$m (L _1) = 2 cos x _o$


$m(N) = \dfrac {+1}{2 cos x _o}$

$m(N) = \dfrac {+1}{2 cos x _o} = 1$

$cos x _o = \dfrac {1}{2}$

      $x _o = \dfrac {\pi}{3}$

        $y = 2sin (\dfrac {\pi}{3}) = \sqrt {3}$

Multiple choice physics light : reflection and refraction from plane surface introduction to light and mirror magic with mirrors image formation by plane mirror principle of reversibility of path of light refractive index

When a plane mirror is rotated through an angle $\theta$, the reflected ray rotates through an angle $2\theta$. Then the size of the image 

  1. is halved

  2. is doubled

  3. remains unchanged

  4. is quadrupled
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When a plane mirror is rotated through an angle $\theta$ , then the reflected ray rotates through an angle 2$\theta$; but the size of the image remain the same.

Multiple choice physics light and shadow formation of image by a pinhole camera pinhole camera shadow

A small plane mirror kept at the centre of a sphere of diameter $3\ m$, makes $12$ revolution per second. A thin light beam is made incident on the mirror. The linear speed of the light spot on the sphere, formed after reflection from the mirror is :

  1. $18\pi\ m/s$
  2. $36\pi\ m/s$
  3. $72\pi\ m/s$
  4. $144\pi\ m/s$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When plane mirror rotates through an angle $\theta$ , the reflected ray rotates through an angle 2$\theta$. So spot on the screen will make 2 x 12 = 24  revolution per second.

 
To find the velocity 
v=2$\pi$R x frequency 
=2$\pi$ x 3 x 24
=144$\pi$ m/s

 D is the Correct answer.
 

Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

Formation of erect image is a characteristic of which of the following mirrors ?

  1. Plane Mirror

  2. Concave mirror

  3. Convex mirror

  4. All the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
$ \bf{Convex\ mirrors} $ always produce a virtual, erect and diminished image and the decrease in size of image depends on the position of the object in front of the mirror.

$ \bf{Plane\ Mirrors} $ always produce a virtual and erect image having the same size as that of the object irrespective of the position of object.

$ \bf{Concave\ mirrors} $ produce real and virtual, erect and inverted, diminished, same-sized and magnified image depending upon the position of the object on the principal axis. The concave mirror forms a virtual and erect image only when the object is placed between the Focus and the pole of the mirror.

Thus, an erect image can be formed by all the three mirrors.

Hence, the correct answer is OPTION D.

Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

Choose the correct option regarding the image formed by a plane mirror

  1. It is real

  2. It is erect

  3. It is inverted

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A $ \bf{plane\ mirror} $ always forms an image which is $ \bf{virtual} $ in nature (meaning that light rays meet behind the mirror or that light rays do not actually come from the image), $ \bf{erect} $ and of the $ \bf{same\ shape\ and\ size} $ as that of the object, it is reflecting.

Hence, the correct answer is OPTION B. 

Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

Which of the following is a characteristic of the image formed by a plane mirror ?

  1. The image is twice in size as the object.

  2. The image is nearer from the mirror as the object is in front of it.

  3. The image is real

  4. The image is erect
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A $ \bf{plane\ mirror} $ always forms an image which is $ \bf{virtual} $ in nature (meaning that light rays meet behind the mirror or that light rays do not actually come from the image), $ \bf{erect} $ and of the $ \bf{same\ shape\ and\ size} $ as that of the object, it is reflecting. The image in  plane mirror is formed as far behind the mirror as the object in front of it. 

Hence, the correct answer is OPTION D. 

Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

When you see your reflection in the inner surface of the spoon, choose the correct option regarding the image formed

  1. The image formed will be erect only, it can not be inverted

  2. The image formed will be inverted only, it can not be erect

  3. The image formed can be both erect or inverted depending upon distance of your face and the spoon

  4. The image formed will be real
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Since inner surface of spoon act as concave mirror i.e. erect or diminished or virtual or real with varyaccording to position of object.

Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

Two plane mirrors are inclined to each  other such that  a ray of light incident on the first  mirror $\left( { M } _{ 1 } \right) $ and parallel to the second mirror $\left( { M } _{ 2 } \right) $  is finally reflected from the second mirror $\left( { M } _{ 1 } \right) $ parallel to the two mirroes will  be : 

  1. ${ 90 }^{ 0 }$
  2. ${ 75 }^{ 0 }$
  3. ${ 45 }^{ 0 }$
  4. ${ 60 }^{ 0 }$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

For two mirrors inclined at angle θ, a ray incident parallel to one mirror and exiting parallel to the other after two reflections requires θ = 60°. This can be derived using the fact that the angle of incidence equals angle of reflection, and the total deviation after two reflections is 2θ. The specific path described requires this specific angle.

Multiple choice evs magic with mirrors image of an extended object formed by a plane mirror reflection at plane surface introduction to light and mirror

If the mirror is displaced by a distance 4 cm, towards the object, the image is displaced by 

  1. 12 cm

  2. 4 cm

  3. 6 cm

  4. 8 cm
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When a plane mirror is moved by a distance x towards an object, the image moves by 2x towards the object because the distance between the object and the image is reduced by 2x.

Multiple choice maths enlargement and scale drawing dilation enlargement similarity as a size transformation mapping mapping space around us bearing and drawings

If one shape becomes another using rotation / reflection, then the shapes are __________.

  1. similar

  2. congruent

  3. mirror images

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If the size of the figure does not get affected by rotation or reflection, then the figure will remain same and it will be congruent.

Multiple choice physics option c: imaging the mirror formula derivation of formula for curved mirrors mirror formula and magnification

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

  1. positive

  2. negative

  3. unity

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

Multiple choice physics option c: imaging the mirror formula derivation of formula for curved mirrors mirror formula and magnification

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

  1. positive

  2. negative

  3. unity

  4. infinity
Reveal answer Fill a bubble to check yourself
B Correct answer
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.