| Q1: |
what will be the reverse path of the light when travelling from denser to rarer medium and creates a refraction of 90' from the normal |
Ancoor |
29/9/2013 |
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| Q2: |
why there is no phase change in refraction,but phase changes by pi in case of reflection from denser medium? |
Surbhi |
5/2/2013 |
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| Q3: |
Which principle of light is used in vision |
Barbie |
4/10/2010 |
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| Q4: |
why we can't see the sound waves. |
M ASMAR |
30/9/2010 |
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| Q5: |
why light can't refrect when enter parallal to the normal. |
M ASMAR |
30/9/2010 |
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| Q6: |
is the intensity of light reduced when it passes into another medium?. |
hosea joseph bulashi |
6/7/2010 |
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| Q7: |
how does light rays behave when it pass from air and water? |
nino |
5/7/2010 |
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| Q8: |
Why does light refract towards the normal as it passes from rare medium to optically dense medium? why not away from the normal? |
Amaha Araya |
13/3/2010 |
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| Q9: |
Which two materials provide the most refraction of light |
vikkii |
31/3/2009 |
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| Q10: |
is the principle of optical reversibility posiible in the case of total internal reflection of light |
anil pillai |
8/9/2008 |
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| Q11: |
when light falls perpendicular to glass slab why refraction doesnt take place while it is changing its medium as well? And on changing medium speed also changes,why this happens? |
tooba |
16/7/2008 |
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| Q12: |
Why there is no refraction when light falls perpendicular to glass slab? |
AJIALEX |
21/6/2008 |
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| Q13: |
A person is able to see objects clearly only when these are lying at distances between 50cm and 300cm from his eye.What kind of defects of vision he is suffering from/ |
AJIALEX |
21/6/2008 |
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| Q14: |
why refraction doesnot takes place in normal incidence? i want an answer in physical sence, not in the mathematical sence. |
girisn |
22/5/2008 |
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| Q15: |
A ray of light enters from a rarer to denser medium, the angle of incidence is 'i' then the reflected and the refracted rays are mutually perpendicular to each other. The critical angle for the pair of media."Is this question valid ?" |
Vivek |
20/4/2008 |
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| Q16: |
why total internal reflection cannot take place when light travelling through a rarer medium enters a denser medium? |
hamza |
10/3/2008 |
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When light travels from a rarer to denser medium it bends towards the normal, the condition for total internal reflection requires the ray to bend away from the normal till 90 degree angle is attained. In the rarer to denser case if the incident ray is at 0 degree ( parallel to normal) the refracted ray is also at 0 that mean it is passing straight through, at 90 degree angle of incident ray there will total internal reflection but then incident ray is actually not passing through rarer medium. Hence it will not be a case of rarer to denser medium refraction. |
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| Q17: |
An old lady can not read a book kept at 25 cm. Which defect of eye is she suffering from? I asked this question earlier. As the lady is old, can she be suffering from presbyopia (due to gradual weakening of ciliary muscles & hence inability to read)? |
pankhuri |
25/1/2008 |
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Okay here goes. The problems could be 1) Cornea, this smooth surface can be damaged by conditions such as blepharitis, an inflammation of the eyelids. More serious symptoms can also occur due to evaporation of the tears and drying out of the corneal surface. This is known as dry eyes. 2) Lens : The lens is also subject to the aging process, and the resulting conditions--cataracts and presbyopia. The clouding of the lens--or cataract—results in diminished vision. A hardened lens becomes more fixed on distant objects and cannot focus as well on nearby objects or vice versa, this is known as presbyopia. 3) Retina : Macular degeneration (loss of central retinal function) and glaucoma (damage to the optic nerve due to increased intraocular pressure) can also take place. |
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| Q18: |
An old lady can not read a book kept at 25 cm. Which deffect of eye is she suffering from? |
pankhuri |
23/1/2008 |
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Hyperopia, or farsightedness |
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| Q19: |
What is the power of accomodation of a healthy human eye? |
pearl |
23/1/2008 |
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The ability of the eye to adjust its focal length is known as accommodation. The eye accommodates by assuming a lens shape that has a shorter focal length. A healthy eye is able to bring both distant objects and nearby objects into focus without the need for corrective lenses. The maximum variation in the power of the eye is called the Power of Accommodation. A young human eye can change focus from distance to 7 cm from the eye in 350 milliseconds. This dramatic change in focal power of the eye of approximately 15 diopters. |
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| Q20: |
what is an emergent ray,refracted ray, angle of incidence and angle of refraction? |
jane |
15/9/2007 |
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Hi Jane, you need to refer some basic book on light, ours is not a homework help site but a concept help site, I will be glad to help you with your concepts and with understanding theory but not with basic definitions that you can find in any textbook or websites. Do revert with your confusions, problems and be assured we will assist you. All the best - Admin |
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| Q21: |
analogy between refraction and a car moving from road onto marshy land |
zaynah |
15/8/2007 |
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A car moving along the road turns into the sidewalk of gravel or sand, the wheel first meeting the sand slows down due to resistance but the second wheel is still moving at the same speed as it is on the road, hence the car experiences a turning motion or change in angle. Once all wheels are in sand the car moves in a straight line again |
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| Q22: |
WHAT WILL BE THE ANGLE OF REFRACTION IF THE ANGLE OF INCEDENCE IS EQUAL TO 50 DEGREES |
SOURAV |
11/5/2007 |
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Air water – 35.2 degrees, please use Snell’s law to calculate the angle of refraction for other mediums example air glass, air oil, air diamond or a combination of these |
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| Q23: |
Does the lateral displacement of light increase as its angle of incidence increases? |
kay |
12/2/2007 |
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Yes it does, lateral displacement is directly proportional to angle of incidence, it tends to maximum as angle of incidence approaches 90 degree. |
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| Q24: |
do all wavelengths i.e.blue,green,red,indigo travel at constant speed in air or vacum? |
mihir |
12/11/2006 |
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Yes and no, all electromagnetic radiations (including colors of light) travel at the same speed in vacuum, but in air or any other medium the speeds are different (or they undergo refraction), the denser a medium is the higher will be the reduction in speed and more prominent will be the refraction, this is why dispersion is prominent when light is passed thru a glass prism, a highly dense medium but is not at all prominent when it passes thru a rare medium like air. |
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| Q25: |
why does the light ray bend towards the normal when travels from rarer medium to denser medium? |
suhas |
21/9/2006 |
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Bending of light due in refraction is primarily due to change in speed of its wavefront when it meets a different medium. The part closer to medium slows down causing a bending. |
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| Q26: |
what is lateral displacement on plane refractors? |
hart |
12/9/2006 |
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A ray of light emerges out a glass slab in a direction parallel to its entry but displaced in the x direction due to refraction. This is the lateral (horizontal) displacement. This mainly happens because of parallel faces of a glass slab, if the glass slab’s second face was not parallel the light would disperse into its component colors as it does in a prism. |
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| Q27: |
what is a light? |
sajjadh |
4/4/2006 |
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The answer for this will not satisfy you because it could be simple one like light is an electromagnetic radiation with its wavelength lying in the visible range or could be complicated enough to spill beyond tomes if one were to cover its nature, properties, sources, measurement. There have been many theories written about it and frankly speaking till this day it is still somewhat a mystery. |
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| Q28: |
what is cauchy's constant |
s.viji |
1/4/2006 |
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Cauchy’s constant are a part of dispersion for relationship between a wave length (lambda shown by #) of electromagnetic radiation and the corresponding refraction ratio n where n = a + b/#2+ c/#4 + ···, where a, b, c ··· are constants which characterize the substance and # represents the symbol lambda. Later these were shown to be close to dielectric constants by Helmholtz and kettler using a modified equation |
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| Q29: |
what is gravity well? |
hari |
25/3/2006 |
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Spacetime is thought of as being bent by the presence of mass. This distortion in space-time caused by a massive body such as a planet is called a gravity or potential well. It extends to the surface of the body and has the shape of a four-dimensional paraboloid of revolution, symmetrical about the central mass. Anything on a planet or star is considered to be at the bottom of the gravity well, so to “climb” out of it, requires great energy. The larger a planet is deeper is its gravity well. |
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| Q30: |
is it possible to build time machine? |
alisha |
21/3/2006 |
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Einstein's special theory of relativity allows time travel only in future using gravity well. Traveling back in time brings up Occam razor’s issues of causality, what will happen if you went back and killed your great-grandfather. The spacetime curvature caused by mass-energy and the flow of momentum may produce closed curves making back travel possible, there are many interesting theories out there but practically if someone went back in time, well we are still awaiting his return back… |
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| Q31: |
when light can travel in vaccum why cant sound travel in vaccum? |
sonu |
19/3/2006 |
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Sound is composed of longitudinal waves (alternate compressions and expansions of matter) and in vacuum there is no matter available. Light is composed of transverse waves in an electromagnetic field. There are different views on light travel through vacuum light is considered like a wave and particle together, particles do not require medium. Another theory is it is electromagnetic in nature and has got more to do with one field generating the other so does not need medium |
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| Q32: |
how does light travel? |
shaheen |
9/3/2006 |
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Light can travel in the form of electromagnetic radiation in any medium including vacuum |
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| Q33: |
why the crital angle is 48.75 degrees? |
Alice |
13/2/2006 |
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Critical angles depend on material of medium, optically denser material (more electrons for collision) slow down the light, light speed in vacuum is 299,792 km/s, in air 299702 km/s, in water 225,000 km/s, in diamond 125,000 km/s. Relation is given by n= c/v; for air, n= 1.0003; for water n= 1.33. Hence n (air-water) = n(air)/n(water) = 1.0003/1.33= 0.752. Critical angle n = sin I(critical) / sin R since Sin R=Sin 90= 1; n = sin I(critical) ; since n = 0.752 therefore I(critical) = 48.75 deg |
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| Q34: |
explain two laws of refraction |
madhur |
9/2/2006 |
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Refraction is due to a change in the speed of light as it passes from one medium to another, normally referred to as bending of light, if we take a wavefront of light , as it meets another medium the portion at one end meeting the medium first, slows down while another keeps on moving at the same speed causing a bending of wavefront to occur, once they enter the medium they move together again but with a new speed, the change in speed produces refraction. |
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