G12 Matter & Materials – Optical Phenomena and Properties of Materials
Optical Properties:
1. Reflection of light:
- Phenomenon that leads to scattering
2. Transmission of light:
- Transparent – allows light to pass through
- Translucent – allows some light to pass through
- Opaque – no light passes through
3. Absorption of light:
- Object gains internal energy → increase in temperature or increase in chemical energy
The Photoelectric Effect:
The photoelectric effect: the process whereby an electron is emitted by a metal when light of a particular
frequency shines on it.
Significance of photoelectric effect:
- Establishes quantum theory
- Illustrates particle nature of light
Threshold frequency: the minimum frequency of a light ray must have to emit electrons from a metal.
- If a light ray with a higher frequency than that of the threshold frequency strikes a metal, then
electrons with certain E K will be emitted.
Work function WO: the minimum energy required to emit electrons from a metal without any kinetic energy.
Intensity of light: (amount of light)
- Increase in intensity → increase in electrons emitted (if light ray meets threshold frequency)
- *Doesn’t affect energy of photoelectrons
Optical Properties:
1. Reflection of light:
- Phenomenon that leads to scattering
2. Transmission of light:
- Transparent – allows light to pass through
- Translucent – allows some light to pass through
- Opaque – no light passes through
3. Absorption of light:
- Object gains internal energy → increase in temperature or increase in chemical energy
The Photoelectric Effect:
The photoelectric effect: the process whereby an electron is emitted by a metal when light of a particular
frequency shines on it.
Significance of photoelectric effect:
- Establishes quantum theory
- Illustrates particle nature of light
Threshold frequency: the minimum frequency of a light ray must have to emit electrons from a metal.
- If a light ray with a higher frequency than that of the threshold frequency strikes a metal, then
electrons with certain E K will be emitted.
Work function WO: the minimum energy required to emit electrons from a metal without any kinetic energy.
Intensity of light: (amount of light)
- Increase in intensity → increase in electrons emitted (if light ray meets threshold frequency)
- *Doesn’t affect energy of photoelectrons
