Tag: introduction to light and mirror

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Questions Related to introduction to light and mirror

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

A ray of light is incident on a plane mirror along a vector $\hat {i} + \hat {j} - \hat {k}$, then find the direction of reflected ray if normal is $\hat i + \hat j$

  1. $\hat {i} + \hat {j} - \hat {k}$
  2. $-\hat {i} + \hat {j} - \hat {k}$
  3. $-\hat {i} - \hat {j} - \hat {k}$
  4. $\hat {i} + \hat {j} + \hat {k}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The reflected ray vector r is given by r = i - 2(i.n/n.n)n, where i is the incident ray and n is the normal. Given i = i + j - k and n = i + j, the dot product i.n = 2 and n.n = 2. Thus, r = (i + j - k) - 2(2/2)(i + j) = i + j - k - 2i - 2j = -i - j - k.

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 reflection of your own in the surface of water, Choose the correct option

  1. The image formed is real

  2. The image formed is inverted

  3. The image formed is erect

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

The image formed by surface of mirror is just like that formed by a mirror.

It is virtual and erect.

Answer-(C)

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

The phenomena involves in the reflection of radiowaves by ionosphere is similar to

  1. reflection of light by a plane mirror.

  2. total internal reflection of light in air during a mirage.

  3. dispersion of light by water molecules during the formation of a rainbow.

  4. scattering of light by the particles of air.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The ionosphere is the ionized layer of the Earth's atmosphere and its consists of the ions which are formed due to the UV rays coming from the sun. These free electrons result in the reflection of the radio waves and make them reflected back.


This is same as the mirage formation due to the total internal reflection of the rays when the incident angle is greater than the critical 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

For which of following condition there is no emergent light whatever may be the angle of incidence?

  1. $ A < 2C $
  2. $ A > C $
  3. $ A > 2C $
  4. $ A < C $
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
For this, we can say that if ${ r } _{ 2 }$ (min) is able to do total internal reflection than definitely all values of ${ r } _{ 2 }$ will perform $TIR$ because min ${ r } _{ 2 }$ has performed that, So, for min ${ r } _{ 2 }$, ${ r } _{ 1 }$ has to be maximum hence $i$ will be maximum,
Applying Snell's law we will get $sin{ r } _{ 1 }=\frac { 1 }{ u } =$ critical angle and for no emergence ${ r } _{ 2 }$ min will be consider us greater than critical angle and hence rest ${ r } _{ 2 }$ will be automatically eligible for $TIR$.
For relation,
${ r } _{ 1 }+{ r } _{ 2 }=A$
We will get ${ r } _{ 1 }+{ r } _{ 2 }=A$
we will get, ${ r } _{ 1 }+{ r } _{ 2 }>2$ (critical angle)
$A>2$ critical angle.