What is the direction (vertical or horizontal) of the transmission axis of Polaroid sunglasses? Give the physical reason for your answer.

Polaroid filters are incorporated into sunglasses. Because the light reflecting off most surfaces will tend to be partly polarized with a predominance of the electric fields oscillating horizontally, that “glare” can be diminished by having the transmission axis of the Polaroid filters aligned vertically.

http://www.physics.uc.edu/~sitko/LightColor/16-Polarization/polarization.htm

The transmission axis of Polaroid sunglasses is vertical. The physical reason behind this is that Polaroid sunglasses are designed to block horizontally polarized light while allowing vertically polarized light to pass through.

To understand why the transmission axis is vertical, we need to start with a basic understanding of polarization. Light is an electromagnetic wave, and it vibrates in all directions perpendicular to its direction of propagation. When this vibration is restricted to a single plane, it is said to be polarized.

Polarizing filters, like those used in Polaroid sunglasses, work by allowing only light waves that are vibrating in a specific direction to pass through while blocking those vibrating in other directions. The filter consists of long chain-like molecules aligned in a specific way, often by stretching a plastic sheet during manufacturing.

The orientation of these molecules within the polarizing filter determines the transmission axis. In the case of Polaroid sunglasses, the molecules are aligned vertically, which means they are oriented in a way that allows vertically polarized light to pass through but blocks horizontally polarized light. This arrangement is chosen because horizontally polarized light tends to cause more glare, especially when it reflects off flat surfaces like water or the road.

So, to answer your question, the transmission axis of Polaroid sunglasses is vertical to block horizontally polarized light and reduce glare.