Hello!I was wondering if anybody had the time to help me with this question. I am not sure what equation to use with three polarizing filters! I thought we use Malus' Law, but doesnt seem to work. Any help would be greatly appreciated!!
The question: Unpolarized light passes through three polarizing filters. The first one is oriented with a horizontal transmission axis, the second filter has its transmission axis 25.7° from the horizontal, and the third one has a vertical transmission axis. What percent of the light gets through this combination of filters?
a)92.4%
b)50%
c)0%
d)7.6%
What I've done so far:
Malus' Law=I=(I_0)*cos^2(theta)
If theta=25.7,
then I=0.812(I_0)
Times by 100 = 81.2?
Thank you so much in advance!
It's 0%, I've done the exact same question, I think there's a typo.
It's not 0%
To find the percent of light that gets through the combination of filters, we can use Malus' Law. However, the way you applied the equation seems to be incorrect.
Malus' Law states that the intensity of light transmitted through a polarizing filter is proportional to the square of the cosine of the angle between the transmission axis of the filter and the polarization direction of the incident light.
In this case, we have three filters:
1) The first filter has a horizontal transmission axis. Since the incident light is unpolarized, the orientation of the first filter doesn't affect the transmitted intensity. So, the intensity of light transmitted through the first filter would be I1 = I0, where I0 is the initial intensity.
2) The second filter has its transmission axis 25.7° from the horizontal. To calculate the transmitted intensity through this filter, we need to use the equation I2 = I1 * cos^2(θ2), where θ2 is the angle between the transmission axis of the second filter and the polarization direction of the incident light. Since the angle is given as 25.7°, we have θ2 = 25.7°. Substitute this into the equation and calculate I2.
3) The third filter has a vertical transmission axis. Similarly, we use the equation I3 = I2 * cos^2(θ3), where θ3 is the angle between the transmission axis of the third filter and the polarization direction of the incident light. In this case, the incident light is already polarized in the horizontal direction after passing through the second filter. Thus, the angle between the polarization direction and the transmission axis of the third filter is 90°, so θ3 = 90°. Calculate I3 using this equation.
Finally, the percent of light that gets through the combination of filters is given by (I3 / I0) * 100. Calculate this ratio and compare it to the answer choices to determine the correct option.
By following these steps, you will be able to find the correct answer to the question.