VCE Stuff > VCE Physics

can someone please explain this to me.

<< < (2/3) > >>

mozart:
but doesn't the ^2 when put on the I and r change the equation?

Collin Li:
I'm not sure what you mean.

mozart:
because you said "put them together and you get
I . r^2 = k to I^1 . (r^1)^2 = I^2 . (r2)^2 " and by putting the ^2 in front of the second part of this equation which is I^2 . (r2)^2 , wouldn't it change the equation because your putting the ^2 there. If i'm not explaining it clearly, this is what i mean.

If you use the inverse law you'd get k = I . r^2
but how did you end up with adding the extra bit to this equation I^2 . (r^2)^2
why would you add it anyway?


sorry for the hassle

Collin Li:
I see what you mean. It's actually okay to do that, because just means intensity under one set of conditions (depends on ), while means intensity under another set of conditions (depends on ).

Oh, you can actually do it this way (might be easier to understand):



Substitute in: and





Now, using that equation, substitute , and solve for

This is exactly the same as what I was doing before, except I was doing it in algebra so it may have been confusing, especially with all the subscripts (like ) and superscripts (like ).

You were confusing me with your "^2", it should be "_2" to signify the subscript.
Superscript: (notation: x^2)
Subscript: (notation: x_2)

cara.mel:
The mirror one is possible at right angles. You'd get the 2 images you'd expect from looking into one mirror only, and another one at the corner where they join.

How to explain it I don't remember. I was trying to draw it out but got stuck xD. It has something to do with another image being formed from the reflected images. Because they're at right angles, they'll overlap each other and you'll only get 1 more image

Like this lovely drawing:


If they were at acute angles you'd get more :)

In my frustration I googled it.
http://www.physicsclassroom.com/Class/refln/U13L2f.html
Look at the picture with the 2 red 2 blue and green dots in it. Each set beyond the red one is formed by the image 'reflecting' off the other mirror, obeying all the rules you already know (perpendicular to it etc). They don't explain it very well (and their right angle mirror explanation on the other page I don't really get either xD) so say if you want me to explain it further, I just think it makes more sense seeing mirrors not at 90º, and then applying it back to the 90º situation

Navigation

[0] Message Index

[#] Next page

[*] Previous page