Question

How must you orient polarizing filters to block out all light?

1) Parallel to each other
2) Perpendicular to each other
3) At a 45-degree angle to each other
4) At a 90-degree angle to each other

Answer 1

Polarizing filters must be oriented with their axes perpendicular to each other, which is at a 90-degree angle, to block out all light.

Step-by-step explanation:

To block out all of the light using polarizing filters, the filters must be oriented so that their axes are perpendicular to each other. If the first polarizing filter polarizes the light along its axis, all of the light passed by the first filter will be blocked by the second filter when it is rotated to be perpendicular (90 degrees) to the first. This occurs because only the component of the light that is parallel to the axis of the second filter can pass through, and when the filters are perpendicular, there is no component of the light that matches this condition, thus, no light passes through.