Tag: magic with mirrors

Questions Related to magic with mirrors

A real image of a distant object is formed by a plano-convex lens on its principal axis. Spherical aberration

evs magic with mirrors introduction to light and mirror image formation by plane mirror light : reflection and refraction from plane surface

  1. is absent

  2. is smaller if the curved surface of the lens faces the object

  3. is smaller if the place surface of the lens faces the object

  4. is the same whichever side of the lens faces the object

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Correct Option: B

In case of reflection by a plane mirror, which of the following statement are not correct?

evs magic with mirrors introduction to light and mirror image formation by plane mirror light : reflection and refraction from plane surface

  1. It can never give real image

  2. It can never give inverted image

  3. It changes left into right

  4. It changes front into back

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Correct Option: A,B,D
Explanation:

In case of reflection an by a plane mirror, it does not give a real, inverted image and image never changes front into back.

An object is placed symmetrically between the two plane mirrors inclined at angle of $30^o$. Then the total number of images formed is:

evs magic with mirrors introduction to light and mirror image formation by plane mirror light : reflection and refraction from plane surface

  1. 12

  2. 2

  3. 11

  4. 15

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Correct Option: C
Explanation:

No. of image $ = \dfrac{ 360^{\circ}}{ \theta} – 1$

                                             $ = 12-1$
                                             $ = 11$

It is necessary to illuminate the bottom of a well by reflected solar beam when the light is incident at an angle of $\alpha = {40}^{\circ}$ to the vertical. At what angle $\beta$ to the horizontal should a plane mirror be placed?

evs magic with mirrors introduction to light and mirror image formation by plane mirror light : reflection and refraction from plane surface

  1. ${70}^{\circ}$

  2. ${20}^{\circ}$

  3. ${50}^{\circ}$

  4. ${40}^{\circ}$

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Correct Option: A

Which of the following is a reflector of light?

evs magic with mirrors introduction to light and mirror image formation by plane mirror light : reflection and refraction from plane surface

  1. Sun

  2. Moon

  3. Star

  4. Filament

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Correct Option: B
Explanation:

Moon does not have any light of its own, it reflects the light of the sun.

A plane mirror is in a vertical plane and is rotating about a vertical axis at 100 mm horizontal beam of light is incident on the mirror. The reflected beam will rotate at

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

  1. $100 rpm$

  2. $141 rpm$

  3. $0 rpm$

  4. $200 rpm$

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Correct Option: D

When a mirror is rotated through an angle, the reflected ray moves through double that angle, the instrument based on the above principle is :

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

  1. Periscope

  2. Odometer

  3. Refractometer

  4. Sextant

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Correct Option: D
Explanation:

A periscope is based on the principle of reflection.

An Odometer is used to measure the distance travelled by a vehicle.
A Refractometer is based on the principle of refraction (Snell'slaw).
A Sextant is used to measure the angle between two visible objects. Baesd on the principle that when a mirror is rotated through an angle the reflected ray moves through double of that angle.

A source of light lies on the angle bisector of two plane mirrors inclined at an angle $\theta$. The values of $\theta$, so that the light reflected from one mirror does not reach the other mirror will be

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

  1. $\theta \geq 120^0$

  2. $\theta \geq 90^0$

  3. $\theta \leq 120^0$

  4. $\theta < 30^0$

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Correct Option: A

In a Michelson experiment for measuring speed of light, the distance traveled by light between two reflections from the rotating mirror is 4.8 km. The rotating mirror has a shape of a regular octagon. At what minimum angular speed of the mirror (other than zero) the image is formed at the position where a non-rotating mirror forms it?

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

  1. $780$ $rev/s$

  2. $7800$ $rev/s$

  3. $690$ $rev/s$

  4. $7500$ $rev/s$

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Correct Option: B
Explanation:

Minimum angular speed $ f=\dfrac { c }{ dN }$


$ =\dfrac { 3\times { 10 }^{ 8 } }{ 4.8\times { 10 }^{ 3 }\times 8 }$

$ =7812rev/s\cong 7800rev/s$

A plane mirror which rotates $10^4$ times per minute reflects light on to a stationary mirror $50$ m away. This mirror reflects the light normally so that it strikes the rotating mirror again. The image observed in the rotating mirror is shifted through $2.4$ minutes from the position it occupies. When the rotating mirror is stationary, what is the speed of light?

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

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

  2. $4\times 10^8$ m/s

  3. $5\times 10^8$ m/s

  4. $6\times 10^8$ m/s

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Correct Option: A