Tag: reflection of light and shadow

Questions Related to reflection of light and shadow

Fill in the blank:

When angle of incidence increases, glancing angle of incidence ________.

physics reflection of light and shadow terms related with reflection terms related to reflection of light laws of reflection

  1. decreases

  2. increases

  3. remains same

  4. becomes zero

Show answer
Correct Option: A
Explanation:

Angle of incidence $+$ Glancing angle of incidence $=90^0$

So, Glancing angle of incidence $=90^0 -$ Angle of incidence
This means, when angle of incidence increases, glancing angle of incidence decreases,

Fill in the blank:

When the angle of incidence increases, glancing angle of reflection _______.

physics reflection of light and shadow terms related with reflection terms related to reflection of light laws of reflection

  1. increases

  2. remains same

  3. decreases

  4. becomes infinite

Show answer
Correct Option: C
Explanation:

Angle of incidence $+$ glancing angle of incidence $=90^0$

So, glancing angle of incidence $=90^0 -$ angle of incidence
Now, glancing angle of incidence $=$ glancing angle of reflection
Therefore, glancing angle of reflection $=90^0 -$ angle of incidence
This means, when angle of incidence increases, glancing angle of reflection decreases,

Bouncing of light into the same medium, from which the light ray is incident, is termed as

physics reflection of light and shadow terms related with reflection terms related to reflection of light laws of reflection

  1. Refraction

  2. Diffraction

  3. Reflection

  4. Scattering

Show answer
Correct Option: C
Explanation:

$ \bf{Refraction} $ of light is the phenomenon of bending of light or change in the direction of light, when it passes obliquely from one transparent medium to another.

$ \bf{Diffraction} $ is the phenomenon of bending of light waves around the corners of an obstacle or aperture, placed in the path of light beam.

$ \bf{Reflection} $ is the phenomenon in which light rays on striking a polished surface(such as a mirror) bounce back or are sent back into the same medium. 

$\bf{Scattering} $ is the phenomenon by which a beam of light is redirected or deflected in many different directions when it passes through an imperfect medium due to the interaction with the particles of the medium.

Hence, the correct answer is OPTION C. 

Reflection can occur on

physics reflection of light and shadow terms related with reflection terms related to reflection of light laws of reflection

  1. Transparent surfaces

  2. Translucent surfaces

  3. Opaque surfaces

  4. B and C

Show answer
Correct Option: D
Explanation:
Objects which allow the light to pass through them completely without any obstruction are called $ \bf{transparent} $ objects.
Objects which allow the light to pass through them partially are called $ \bf{translucent} $ objects.
Objects which do not allow the light to pass through them are called $\bf{opaque} $ objects.

Since, transparent objects allow light to pass through them completely, no reflection can occur on them. 

Reflection occurs on translucent surfaces because they reflect a certain amount of light while allowing a certain amount of light to be transmitted. Reflection occurs perfectly on Opaque surfaces because they reflect all the light that falls on them without allowing any light to pass through them.

Hence, the correct answer is OPTION D.

Which of the following is the main reason of Opacity of light waves.

physics reflection of light and shadow terms related with reflection terms related to reflection of light laws of reflection

  1. reflection

  2. absorption

  3. refraction

  4. diffusion

  5. transmission

Show answer
Correct Option: A
Explanation:

Objects are visible to the eye when light strikes the surface and reflects back itself into the eye. Opaque objects show this phenomenon.

However in the transparent objects, the incident light on their surface gets transmitted, hence does not reflect back to eye and appear transparent.

A ray of light striking a plane mirror at an angle of 35 degrees with the normal.

Find out the angle of reflection with normal.

physics reflection of light and shadow terms related with reflection terms related to reflection of light laws of reflection

  1. 35 degrees.

  2. 55 degrees.

  3. 10 degrees

  4. 90 degrees

  5. 125 degrees

Show answer
Correct Option: A
Explanation:

Angle of incidence    $i = 35$ degrees

According to Snell's law of reflection, the angle of incidence is equal to the angle of reflection.
$\implies$ Angle of reflection      $r = i = 35$  degrees

When a light ray falls on a perfectly reflective mirror at an angle. Identify which of the following statement is true about the ray?

physics reflection of light and shadow terms related with reflection terms related to reflection of light laws of reflection

  1. The frequency of the light ray changes

  2. The wavelength of the light ray changes

  3. The velocity of the light ray changes

  4. The period of the light ray changes

  5. The direction of motion of the light ray changes

Show answer
Correct Option: E
Explanation:

When a light ray falls on a perfectly reflective mirror at some angle, then only the direction of the light rays changes such that the angle of incidence is equal to the angle of reflection but the frequency, wavelength, time period and the velocity of the light remain constant.

Thus option E is correct.

Identify on which of the following, specular reflection would most likely to occur. 

physics reflection of light and shadow terms related with reflection terms related to reflection of light laws of reflection

  1. mirror

  2. wall

  3. sheet of paper

  4. ceiling.

  5. cat's fur

Show answer
Correct Option: A
Explanation:

The back of a mirror is usually covered with some sort of darkly colored, protective material to stop the silver coating from getting scratched, and also to reduce the risk of any light seeping through from behind. Silver reflects light better than almost anything else and that's because it gives off almost as many light as fall on it in the first place.

In which of the following conditions diffuse reflection takes place?

physics reflection of light and shadow terms related with reflection terms related to reflection of light laws of reflection

  1. When a parallel beam of light is reflected by a plane mirror.

  2. When a parallel beam of light is reflected by a highly polished metal surface.

  3. When a parallel beam of light is reflected by a paper sheet.

  4. All of these

Show answer
Correct Option: C

A person has a $18$cm wide face and his two eyes are separated by 8 cm.Find the minimum width of a mirror required for the person to view is face laterally is

physics reflection of light and shadow terms related with reflection terms related to reflection of light laws of reflection

  1. $9$cm

  2. $4$cm

  3. $5$cm

  4. $13$cm

Show answer
Correct Option: C
Explanation:

For minimum width -

i). Center of face and mirror must lie in perpendicular bisector of the line joining two eyes.
ii). Left eye must see right end point of face at the end of the mirror.
iii). Night eye must see left end point of face at then end of the mirror.
Now let, 
$F _1,F _2$ end points of face width $11E _1,E _2$ two eyes $11C-$ center of face.
$m _1.m _2-$ mirror end points
$m _1,m _2-$ projection of $m _1m _2$ on line joining two eyes.
Now, line joining two eyes should look like -
$F _1--E _1---m _1-C---m _2----E _2---F _2$
Due to symmetry,
$\Rightarrow F1E2=E1F2=13cm$
Also, $m _1,m _2$ must be midpoint of $F1E2$ and $E1F2$ respectively.
So, $E1m2=m1E2=\dfrac{13}{2}=6.5$
$E1m2=6.5$
$\Rightarrow E1C+Cm2=6.5$
     $4+Cm2=6,5$
     $Cm2=2.5$
similarly $m1C=2.5$
$\Rightarrow m1m2=m1C1C2=5cm=$ mirror width.
Hence, the answer is $5cm.$