IB MYP 4-5 Physics- Electromagnetic radiation- Study Notes - New Syllabus
IB MYP 4-5 Physics-Electromagnetic radiation- Study Notes
Key Concepts
- Electromagnetic radiation
Electromagnetic Radiation
Electromagnetic Radiation
Electromagnetic (EM) radiation is a form of energy that travels through space as oscillating electric and magnetic fields.
- It does not require a medium , it can travel through vacuum (unlike sound).
- EM waves are transverse waves, meaning the oscillations of the electric and magnetic fields are perpendicular to the direction of wave propagation.
- They all travel at the same speed in vacuum:
\(c = 3.0 \times 10^{8} \, \text{m/s}\)
- They can transfer energy from one place to another without the movement of matter.
The Electromagnetic Spectrum
The EM spectrum is the full range of all electromagnetic waves, arranged according to wavelength (\(\lambda\)) or frequency (\(f\)).
- Relationship:
\(c = f \lambda\)
- Relationship:
Order (longest wavelength → shortest wavelength):
- Radio waves
- Microwaves
- Infrared radiation (IR)
- Visible light
- Ultraviolet (UV)
- X-rays
- Gamma rays
Properties of Electromagnetic Waves
- Travel at the speed of light in vacuum (\(3 \times 10^{8}\, \text{m/s}\)).
- Do not need a medium (can travel through space).
- Can be reflected, refracted, diffracted, and absorbed.
- Carry energy and momentum.
- Shorter wavelength → higher frequency → higher energy.
Example:
Explain why microwaves are used in satellite communication.
▶️ Answer/Explanation
Microwaves can pass easily through the atmosphere without much absorption or scattering.
They travel at the speed of light and can carry large amounts of information over long distances.
Final Answer: \(\boxed{\text{Microwaves are suitable because they penetrate the atmosphere and carry signals effectively.}}\)
Example:
Why are X-rays used in medical imaging instead of visible light?
▶️ Answer/Explanation
Visible light cannot penetrate human tissues, so it cannot show internal structures.
X-rays have very short wavelengths and high energy, allowing them to pass through soft tissue but not dense bones.
This creates a contrast image useful for doctors.
Final Answer: \(\boxed{\text{X-rays are used because they penetrate tissue but are absorbed by bones, producing clear internal images.}}\)