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Questions Related to physics

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

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

  1. mirror

  2. wall

  3. sheet of paper

  4. ceiling.

  5. cat's fur
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

In which of the following conditions diffuse reflection takes place?

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Diffuse reflection occurs when light hits a rough or irregular surface, causing it to scatter in many directions. A paper sheet has a microscopically rough surface compared to mirrors or polished metal, which produce specular reflection.

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

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

  1. $9$cm

  2. $4$cm

  3. $5$cm

  4. $13$cm
Reveal answer Fill a bubble to check yourself
C Correct answer
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 $5cm.$

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

A beam of light converges at point $P$. Now, a plane mirror is placed $20 \mathrm { cm }$ before the converging point $P$. The new converging point is

  1. $20 \mathrm { cm }$ infront of the mirror

  2. $20 \mathrm { cm }$ behind the mirror

  3. The separation between new converging point and previous converging point is $40 \mathrm { cm } $

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

A converging beam directed at a point 20 cm behind a mirror will reflect and converge at a point 20 cm in front of the mirror due to the law of reflection. The mirror effectively flips the virtual image of the convergence point.

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

What is the correct definition of reflectance?

  1. Difference between amount of light absorbed by the surface and amount of light reflected.

  2. The amount of light reflected by a surface is known as reflectance.

  3. The ratio of the amount of the light reflected from a surface to the amount of light falling on the surface is called reflectance.

  4. The ratio of amount of light falling on a surface to the amount of light reflected on the surface is called reflectance.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to definition, ratio of the amount of light reflected from a surface to the amount of light falling on the surface is called reflectance.

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

The angle formed between the incident ray and the normal is called _____________

  1. angle of incidence

  2. angle of reflection

  3. angle of refraction

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

Angle of incidence is the angle between incident ray and normal to the reflecting surface at the point of incidence.


Answer-(A).

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

When light rays travelling from one medium fall at the surface of another medium ............ the light rays returns back to the same medium.

  1. All of

  2. Part of

  3. None of

  4. Can't be determined
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When light rays traveling from one medium fall at the surface of another medium part of the light rays returns back to the same medium.
For example in window mirror we can see our image and we can also see outside objects because of both reflection and refraction of light.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation density of a fluid density of fluid density and relative density

By cooling two liquids of equal volume from temperature $60 ^ { \circ } \mathrm { C }$  to $50 ^ { \circ } \mathrm { C }$ in same conditions time required are 324 and 810 sec respectively. If ratio of specific heat of both are 3:4. Then ratio of their. densities (water equivalent of calorimeter is negligible ):

  1. 3 /4

  2. 4 /9

  3. 8 /15

  4. 9 /20
Reveal answer Fill a bubble to check yourself
A Correct answer