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Electromagnetic Waves: Understanding the Spectrum in A-Level Science
What Are Electromagnetic Waves?
Electromagnetic (EM) waves are oscillating electric and magnetic fields that travel through space at the speed of light (
).
Key Properties of Electromagnetic Waves
Transverse Nature
EM waves are transverse, meaning the electric and magnetic fields oscillate perpendicular to each other and the direction of wave propagation.
Wave Equation
![\[ c = f\lambda \]](https://skinattuition.co.uk/core/ql-cache/quicklatex.com-fca565ca9b8bdc277eabd91b1aae752a_l3.png "Rendered by QuickLaTeX.com")
Where:
: Speed of light (m/s)
: Frequency (Hz)
: Wavelength (m)
: Speed of light (m/s)
: Frequency (Hz)
: Wavelength (m)The Electromagnetic Spectrum
The EM spectrum is divided into regions based on wavelength and frequency:
- Radio Waves: Longest wavelength, used in communication
- Microwaves: Used in cooking and satellite transmissions
- Infrared (IR): Heat radiation
- Visible Light: Detected by the human eye
- Ultraviolet (UV): Causes sunburns, used in sterilization
- X-Rays: Penetrate soft tissue, used in medical imaging
- Gamma Rays: Highest energy, used in cancer treatment
Photon Energy
The energy of a photon is given by:
![\[ E = hf \]](https://skinattuition.co.uk/core/ql-cache/quicklatex.com-c7528b3a4f027a35c3b419ab61cb0ab7_l3.png "Rendered by QuickLaTeX.com")
Where 
(Planck’s constant).
Example: Calculate the energy of a photon with 
:
![\[ E = hf = 6.63 \times 10^{-34} \times 5 \times 10^{14} = 3.32 \times 10^{-19} \, \text{J} \]](https://skinattuition.co.uk/core/ql-cache/quicklatex.com-f5d6d1b2b087dd918e1796b97971cac4_l3.png "Rendered by QuickLaTeX.com")
Applications of Electromagnetic Waves
Communication
Radio waves and microwaves transmit signals over long distances.
Medical Imaging
X-rays and gamma rays are used to diagnose and treat diseases.
Renewable Energy
Solar panels convert visible and infrared light into electricity.
Common Mistakes in EM Wave Calculations
- Mixing up wavelength and frequency
- Forgetting to convert units for (e.g., nm to m)
- Misinterpreting photon energy calculations
Practice Questions
- Calculate the wavelength of a radio wave with a frequency of
. - Explain how gamma rays are used in cancer treatment.
- Describe one application of microwaves in everyday life.
.