Snell's Law Question

[methylethyl88]

Advertisement - Members don't see this ad

From TBR Physics Example 10.3b

"The material n2 has parallel sides and is surrounded by media n1 and n3. Under which conditions will angle x exceed y?" (Picture included for those who don't have the book)

The answer is that n3 > n1

 

[sangria1986]

theres no question here....

its fairly straightforward so im not sure what you're asking.

 

[orangeANDgreen]

theres no question here....

its fairly straightforward so im not sure what you're asking.

yeah, if n3 is > n1, then the wave should be bent more towards the normal at n2 || n3, so y should be less than x.

 

[Rabolisk]

With problems like these, n2 can be ignored. n1sinθ1 = n2sinθ2 = n3sinθ3. θ1 > θ3 if sinθ1 > sinθ3, or when n3 > n1.

 

[methylethyl88]

With problems like these, n2 can be ignored. n1sinθ1 = n2sinθ2 = n3sinθ3. θ1 > θ3 if sinθ1 > sinθ3, or when n3 > n1.

yes but with snell's law aren't the angles taken from the normal line such the relationship should actually be

n1sin(90-x) = n2sinθ2 = n3sin(90-y)

and if X > Y then shouldn't sin(90-x) < sin(90-y) and therefore n1 > n3?

 

[Rabolisk]

I don't know about you, but those angles (x and y) seem normal to me.

 

[Prateek]

yes but with snell's law aren't the angles taken from the normal line such the relationship should actually be

n1sin(90-x) = n2sin&#952;2 = n3sin(90-y)

and if X > Y then shouldn't sin(90-x) < sin(90-y) and therefore n1 > n3?

If n3 > n1, then a beam of light that goes from n1 to n3 will refract CLOSER to the normal line. Meaning the angle of refraction (theta3) will be smaller than the angle of incidence (theta1)