P1 - Radiation and Waves

Question 1

How does EM get emitted and how does ionisation work?

Answer 1

Everything emits / absorbs. Hotter object emits more. Cooler, absorbs more. Electron can leave atom. Emissions: nuclei change (gamma), energy drop, vibrations (IR). Ionisation, EM absorbed, electron moves up, “excited”, moves down.

Question 2

What are the types of lenses, how does refraction work and how do we see colours?

Answer 2

Boundary crossed, changed speed / direction. Colours, different speed in materials. Prism, dispersed. Object colour is colour absorbed / emitted. Concave, inwards, spreads rays. Convex, outwards, focuses.

Question 3

How do waves behave, what types are there and how can we measure them?

Answer 3

Wave travels, not air / water. Longitudinal, compressions / rarefactions (sound in air). Transverse, water / EM-waves (rope, disturbance 90o). Refraction, more speed change = more direction bend. Different speed / medium.

Question 4

What are the groupings / uses of the EM spectrum, and what are the risks of using EM?

Answer 4

Radio (communication, oscillations), microwaves (heating), IR (temperature), light (internet), UV (heat), X-rays (bones absorb), Gamma-rays (sterilisation). Risks, ionising damages cells, may cause cancer (uncontrolled growth)