Given the RI is 4/3. If the real depth is 64cm, then apparent depth is
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Explanation:
We know that the refractive index of water to air is 4/3 . So,
n=4/3
which should be n = 4/3 = n2/n1 , but my book says,
4/3= real depth/apparent depth.
How have they put the “depths” in the formula and Why?
anw=real depthapparent depth=43
apparent depth=34real depth
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Oct 7 '15 at 19:34
Aaryan Dewan
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Oct 3 '18 at 12:36
user191954
Can you post a picture of the page? – Alec Teal Oct 7 '15 at 19:50
@AlecTeal added – Aaryan Dewan Oct 7 '15 at 19:55
They draw some triangles. Almost everything involved in ray optics is done with a combination of triangles and algebra. Because rays move in straight lines except under specific circumstances and there are lots of theorems abut triangles. – dmckee --- ex-moderator kitten Oct 7 '15 at 20:11
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We can prove this if you dont understand the formula.
Suppose M is a point object at an actual depth MA below the free surface of water XY in a tank.
A ray of light incident on XY normally along MA passes straight along MAA′.Another ray of light from M incident at ∠i on XY,along MB gets deviated away from normal and is refracted at ∠r along BC.If we produce BC we will find that it meets OA at L.Therefore L is virtual image of M which appears when we see from C.Now the apparent depth is AL.
∠AMB=∠MBN′
∠ALB=∠NBC
In ∆AMB,
sini=ABMB
In ∆IAB,
sinr=ABLB
Now,
aμw=ABLB×MBAB=MBLB
Suppose that ∠i→0 then B will near A
Therefore,
aμw=MALA=real depthapparent depth
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May 17 '16 at 6:02
Sikander
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Oct 3 '18 at 12:38
user191954
Can someone help me add an image The image tab is not showing the option for adding image due to poor browser quality. – Sikander May 17 '16 at 6:05
Can you add the image now? – Wolgwang Jan 8 at 7:21
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The picture in this question may be helpful to visualize the situation:
Clarification needed in the concept of apparent depth & real depth
Basically, if you observe an object immersed at some (real) depth h in water, as a consequence of the refraction of light you will see it as if it were at a different (apparent) depth h′. The relation between h and h′ can b easily found geometrically in terms of the angle of incidence (θwater) and angle of refraction (θair). The Snell formula, name
Answer:
48 cm
Explanation:
RI = real depth / apparent depth
∴4/3 = 64 / apparent depth
∴apparent depth = 64 x 3 / 4
∴apparent depth = 16 x 3
∴apparent depth = 48 cm