Unpolrized light passes through 2 polarizers

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Unpolarized light passing through two polarizers at an angle of 28.1° requires the use of the equation I = 0.5 x Io x cos²(theta) to determine the fraction of incident intensity transmitted. The key point is that the problem asks for the ratio of transmitted intensity to incident intensity, not the absolute transmitted intensity. This ratio can be expressed as I/Io = 0.5 x cos²(28.1°). Understanding that the incident intensity is not needed for the calculation of the fraction helps clarify the solution process. The discussion emphasizes the importance of focusing on ratios in intensity problems involving polarizers.
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Homework Statement


Unpolarized light passes through two polarizers whose transmission axes are at an angle of 28.1° with respect to each other. What fraction of the incident intensity is transmitted through the polarizers?


Homework Equations


I=.5xIoxcos^2(theta)


The Attempt at a Solution


Im pretty sure that i have the correct equation, but I'm confused because in the problem I am not given an Incident Intensity, therefore how can i solve for the transmitted intensity? If someone could please start me in the right direction, i would appreciate it very much!
 
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Hi Cheezay,

Cheezay said:

Homework Statement


Unpolarized light passes through two polarizers whose transmission axes are at an angle of 28.1° with respect to each other. What fraction of the incident intensity is transmitted through the polarizers?


Homework Equations


I=.5xIoxcos^2(theta)


The Attempt at a Solution


Im pretty sure that i have the correct equation, but I'm confused because in the problem I am not given an Incident Intensity, therefore how can i solve for the transmitted intensity?
They are not asking for the transmitted intensity, they are asking for the fraction of the incident intensity that is transmitted, which is the ratio of transmitted intensity to incident intensity. Do you see how to solve for that?
 
No, I'm sorry i don't see how to solve for that. I thought maybe it might be 1/2 the incident intensity, but that answer is not correct.
 
Cheezay said:
No, I'm sorry i don't see how to solve for that. I thought maybe it might be 1/2 the incident intensity, but that answer is not correct.

The ratio you're looking for is:

(transmitted intensity) / (incident intensity) = I / Io

Using your equation (from your first post), what is that quantity equal to?
 
Then I/Io= .5 x cos^2(theta). Thanks so much for the help!
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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