Question

Some insect eyes have two types of cells that are sensitive to the plane of polarization of light. In a simple model, one cell type (type H) is sensitive to horizontally polarized light only, and the other cell type (type V) is sensitive to vertically polarized light only. To study the responses of these cells, researchers fix the insect in a normal, upright position so that one eye is illuminated by a light source. Then several experiments are carried out. To vary the angle as well as the intensity of polarized light, ordinary unpolarized light is passed through one polarizer with its transmission axis vertical, and then a second polarizer is placed between the first polarizer and the insect.

When the light leaving the second polarizer has half the intensity of the original unpolarized light, which statement is true about the two types of cells?

a.Only type H detects this light.

b.Only type V detects this light.

c.Both types detect this light, but type H detects more light.

d.Both types detect this light, but type V detects more light.

Answer 1

Both types of cells would detect the light when it has half the intensity of the original unpolarized light, as polarizers at 45 degrees transmit both components equally, making option c correct.

Step-by-step explanation:

When the light leaving the second polarizer has half the intensity of the original unpolarized light, both types of cells detect this light. This occurs because polarizers reduce the intensity of unpolarized light by half when their axes are crossed at an angle of 45 degrees to each other. At this orientation, the light is equally composed of vertical and horizontal components. In the scenario provided, the light passes through the first vertical polarizer and then through the second polarizer, which is positioned at 45 degrees relative to the first one, allowing for the transmission of light with both vertical and horizontal polarization components, but at reduced intensity. Therefore, in the given options, option c is correct: Both types detect this light, but type H detects more light.

Answer 2

b.Only type V detects this light.

Step-by-step explanation:

This is because, the first vertical polarizer reduces the intensity of the light by half. This is because only the vertically polarized light is let through, while the rest it blocked.

Now if the second polarizer was placed in any angle that was not vertical, the intensity of the light would have decreased even more so than half of the original intensity. Since this is not the case, the second polarizer is also placed with its transmission axis vertical.

This means that the light coming out the second polarizer is also vertically polarized like before.

Thus, only the type V cell will detect this light.