Question

give answers guys I will mark as brain list for first answer which is correct​

Answer 1

1. Photoelectric effect is the emission of electrons when electromagnetic radiation, such as light, hits a material.

2. A threshold effect ia a sudden and radical change in a phenomenon which often occurs after surpassing a quantitative limit.

3. Quanta is a very small quantity of electromagnetic energy.

4. Energy is quantized in some system meaning that the system can have only certain energies.