Solving for Intensity of Light Through a Polarizer

In summary, when calculating the intensity of transmitted light passing through a polarizer at an angle of 30.0 degrees, the correct equation to use is I1=I0*cos^2(theta). However, the angle must be in radians instead of degrees, and should be converted by multiplying it by pi/180. Once the correct conversion is made, the intensity of the transmitted light is 0.4875 W/m2.
  • #1
bluey2014
4
0

Homework Statement


Vertically polarized light with an intensity of 0.65 W/m2 passes through a polarizer whose transmission axis is at an angle of 30.0° with the vertical. What is the intensity of the transmitted light?

I0 = 0.65 W/m2
theta = 30.0 degrees

Homework Equations


I1=I0*cos^2(theta)

The Attempt at a Solution


I did:
0.65 W/m2 * cos^2(30.0 degrees) and got I1 = 0.4875 W/m2, but webassign said that was wrong... What am I doing wrong?

Thanks for any help!
 
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  • #2


Hello,

You are on the right track with using the equation I1=I0*cos^2(theta), but there is one small error in your calculation. When using the cosine function, the angle must be in radians instead of degrees. So, you need to convert 30.0 degrees to radians by multiplying it by pi/180.

I1=0.65 W/m2 * cos^2(30.0 degrees * pi/180) = 0.65 W/m2 * cos^2(0.5236 radians) = 0.65 W/m2 * 0.75 = 0.4875 W/m2

So, your final answer is correct. Make sure to always double check your units and conversion factors when working with equations. Keep up the good work!
 

FAQ: Solving for Intensity of Light Through a Polarizer

1. What is a polarizer and how does it affect the intensity of light?

A polarizer is a material that only allows light waves that vibrate in a specific direction to pass through. When light passes through a polarizer, it becomes polarized, meaning the light waves are all vibrating in the same direction. This can reduce the intensity of light, as only a portion of the light is able to pass through the polarizer.

2. How do you calculate the intensity of light after passing through a polarizer?

The intensity of light after passing through a polarizer can be calculated using the Malus' Law equation: I = I0cos2(θ), where I0 is the initial intensity of light and θ is the angle between the polarizer and the direction of the incoming light.

3. Can the intensity of light increase after passing through a polarizer?

No, the intensity of light can only decrease after passing through a polarizer. This is because the polarizer blocks a portion of the light, resulting in a lower overall intensity.

4. How does the angle of the polarizer affect the intensity of light?

The angle of the polarizer, represented by θ in the Malus' Law equation, determines the amount of light that is able to pass through. When θ is 0 degrees, the polarizer is parallel to the incoming light and allows all of it to pass through, resulting in the maximum intensity. As θ increases, the intensity of light decreases until it reaches 0 when θ is 90 degrees.

5. What is the relationship between the intensity of light and the angle of the polarizer?

The intensity of light and the angle of the polarizer have an inverse relationship, meaning as one increases, the other decreases. This is shown by the cosine function in the Malus' Law equation, which decreases as θ increases. As the angle of the polarizer increases, more light is blocked and the overall intensity decreases.

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