Chapter 10b Polorisation

Question 1

What is polarization?

Answer 1

Polarization is a phenomenon that occurs when a transverse wave, like light, is restricted to vibrate in only one direction.** It is one of the most convincing pieces of evidence for the wave nature of light.**

Question 2

What is the difference between polarized and unpolarized light?

Answer 2

Unpolarized light consists of waves vibrating in multiple, random planes. Light from the sun or a light bulb is unpolarized. Polarized light is a wave that has been filtered or reflected so that all its vibrations occur in a single plane.

Question 3

How does a polarizing filter work?

Answer 3

A polarizing filter is a material that transmits the components of a transverse wave that are aligned with its axis, while absorbing the components that are not aligned. This allows it to turn unpolarized light into polarized light.

Question 4

What does the phenomenon of polarization prove about light?

Answer 4

Polarization provides crucial evidence that light is a transverse wave. This is because polarization does not occur for** longitudinal waves.**

Question 5

What is polarization by reflection?

Answer 5

This occurs when unpolarized light reflects from a non-metallic surface, such as water or snow. The reflected light becomes partially polarized.

Question 6

How do polarizing sunglasses reduce glare?

Answer 6

They use polarizing filters to block the horizontally polarized light that reflects off surfaces like water or roads. By absorbing this reflected glare, they make it easier to see.

Question 7

What is Malus’s Law?

Answer 7

Malus’s Law is a principle that states the intensity (I) of a beam of plane-polarized light after passing through a polarizing filter is proportional to the square of the cosine of the angle (θ) between the light’s polarization direction and the axis of the filter.

Question 8

What is the mathematical formula for Malus’s Law?

Answer 8

The formula is I = I_max cos²θ, where I_max is the initial maximum intensity of the light.

Question 9

What happens when two polarizing filters are “crossed”?

Answer 9

If a second polarizing filter (an analyser) is placed at a 90° angle to the first, no light can pass through. The intensity of the light becomes zero because the vertically polarized light from the first filter is completely absorbed by the horizontally aligned second filter.

Question 10

In a two filter seneario what happens to the light intensity as it passes through the first filter?

Answer 10

When unpolarized light passes through one polarizing filter, its intensity is reduced by** half,** becoming polarized with an intensity of I₀/2, where I₀ is the initial intensity. The transmitted light’s polarization is oriented along the filter’s transmission axis.

Question 11

What happens when it passes through the second

Answer 11

its intensity after passing through the second filter is given by Malus’s Law, I = I₀cos²θ, where θ is the angle between the light’s polarization direction and the filter’s axis.