Phase Change & Liquid Crystals

Latent heat of vaporization is:

• The amount of heat energy required to convert a substance from solid to liquid at a constant temperature and pressure.
• The amount of heat energy required to convert a substance from liquid to vapor at a constant temperature and pressure.
• The amount of heat energy required to convert a substance from gas to liquid at a constant temperature and pressure.
• The amount of heat energy required to convert a substance from liquid to solid at a constant temperature and pressure.

The amount of heat energy required to convert a substance from solid to liquid at a constant temperature and pressure is:

• latent heat
• specific heat
• heat of fusion
• thermal energy

latent heat is defined as:

• The heat energy required or released during a phase change of a substance without a change in temperature.
• The heat energy required or released during a change in pressure of a substance.
• The heat energy required or released during a change in temperature of a substance without a phase change.
• The heat energy required or released during a chemical reaction.

latent heat of sublimation is defined as:

• The latent heat of sublimation is the amount of heat energy required to change a substance from a solid directly to a gas without passing through the liquid phase.
• The latent heat of sublimation is the amount of heat energy required to change a substance from a gas directly to a liquid without passing through the solid phase.
• The latent heat of sublimation is the amount of heat energy required to change a substance from a liquid directly to a gas without passing through the solid phase.
• The latent heat of sublimation is the amount of heat energy required to change a substance from a gas directly to a solid without passing through the liquid phase.

Liquid crystal is discovered by:

• Friedrich Reinitzer
• Otto Lehmann
• Hermann von Helmholtz
• Wilhelm Conrad Roentgen

Liquid crystals are defined as:

• A type of crystal that is completely solid
• A type of liquid that is completely transparent
• A state of matter with properties similar to gases
• A state of matter with properties between those of conventional liquids and solid crystals.

What happens when cholesteryl benzoate is heated:

• It turns into a gas.
• It remains in a solid state.
• It decomposes into smaller molecules.
• It undergoes a phase transition from a solid to a liquid state passing through liquid crystal state.

What is the full form of LCD?

• Liquid Crystal Diode
• Light Crystal Display
• Low Contrast Display
• Liquid Crystal Display

Liquid crystals are used in a variety of devices, including:

• LCD displays

• Optical filters

• Temperature sensors

• All of these

The principle behind the operation of an LCD display is:

• The use of magnets to control the display.
• The emission of light from the display.
• The manipulation of liquid crystals to control the passage of light through the display.
• The reflection of light off the display surface.