Question

vi. thinking questions

• does the lcd display the information by emitting the light itself?
• \in this experiment, if the incident light is natural light, then the emitted light should also be natural light\. do you think this conclusion is correct?
• if the light incident on the liquid crystal is linear polarized light, what will happen?

Explanation:

First Question:

LCD (Liquid Crystal Display) works by controlling the passage of backlight (usually from a backlight source like LED) through liquid crystal layers. LCD panels themselves don't emit light; they modulate the light that passes through them (e.g., by aligning liquid crystals to let light through or block it).

Natural light is unpolarized (has vibrations in all directions perpendicular to the propagation direction). When natural light passes through optical elements like polarizers, waveplates, or liquid crystals (which can act as optical modulators), the emitted light can become polarized. For example, if the experiment involves polarizing components (like liquid crystals with polarizers), the emitted light's polarization state will change. So the conclusion that emitted light is still natural light is incorrect.

Liquid crystals can rotate the polarization plane of linearly polarized light (this is called the twisted nematic effect in some LCDs, for example). If linearly polarized light is incident on a liquid crystal (e.g., in a twisted nematic LCD cell), the liquid crystal molecules can rotate the polarization direction of the light. The extent of rotation depends on the liquid crystal's properties (like the twist angle of the nematic phase) and the applied voltage (in an LCD, voltage controls the alignment of liquid crystals). If there are polarizers in the setup (common in LCDs), the rotated polarized light will then interact with the output polarizer (e.g., pass through or be blocked, depending on the polarization direction relative to the output polarizer's axis).

Answer:

No, the LCD does not display information by emitting light itself. It modulates the light from a backlight source (like LED) to create images.

Second Question: