Physics 3.3 - Electromagnetic spectrum.pptx

IGCSE Physics unit 3: 3.3-chapter electromagnetic spectrum

1. Electromagnetic Spectrum The electromagnetic spectrum is the complete range of electromagnetic waves, arranged by their frequency and wavelength. It includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. All these waves travel at the same speed in a vacuum: 3 × 10⁸ m/s. Their energy depends on frequency.

2. Properties of Electromagnetic Spectrum Electromagnetic waves are transverse waves, meaning their electric and magnetic fields vibrate at right angles to each other and the direction of travel. They can reflect, refract, diffract, and interfere, just like light waves. All carry energy and can transfer it to matter. Higher frequency waves carry more energy than lower ones.

3. Light Waves Visible light is the only part of the spectrum that human eyes can detect. It allows us to see objects when light reflects into our eyes. Different wavelengths correspond to different colors. Light waves are used in cameras, microscopes, and optical fibers for communication.

4. Infrared Radiation Infrared radiation has longer wavelengths than visible light and cannot be seen by the human eye. It is mainly felt as heat . All warm objects emit infrared radiation. Infrared is used in thermal cameras, TV remote controls, night-vision equipment, and medical scanners.

5. Ultraviolet Radiation Ultraviolet (UV) radiation has shorter wavelengths than visible light but longer than X-rays. It is emitted by the Sun and can cause tanning and sunburn. Overexposure may damage skin and eyes. UV is used for sterilizing equipment, detecting fake banknotes, and in fluorescent lamps.

6. Radio Waves Radio waves have the longest wavelengths in the spectrum. They carry signals over long distances. They are used in broadcasting radio and TV programs, mobile phones, and satellite communications. Their low frequency makes them suitable for sending information through the atmosphere.

7. Microwaves Microwaves have shorter wavelengths than radio waves. They are absorbed by water molecules, making them useful for cooking in microwave ovens. They are also used in radar, satellite communications, and Wi-Fi technology.

8. X-rays X-rays have very short wavelengths and high energy. They can pass through soft tissue but not bones, making them useful in medical imaging. They are also used in airport security scanners and studying crystal structures .

9. Gamma Rays Gamma rays are the highest frequency and most energetic waves in the spectrum. They are produced by radioactive substances and some cosmic processes. They are used in treating cancer (radiotherapy) and sterilizing medical equipment.

10. Dangers of Electromagnetic Radiation High-energy radiation like UV, X-rays, and gamma rays can damage living cells. They may cause skin cancer, radiation burns, or genetic mutations with long exposure. Proper shielding and controlled exposure are essential for safety.

11. Communication Systems : Analog signals are continuous waves that vary in amplitude or frequency. They can carry sound or images but are easily affected by noise and distortion. Examples: radio broadcasting, old telephone systems, and vinyl records. Digital Signals: Digital signals use binary code (0s and 1s) to transmit information. They are less affected by noise and can be stored or transmitted more reliably. Examples: mobile phones, computers, and modern television . Analog Signals:

12. Conclusion: The electromagnetic spectrum is essential for modern life. It enables communication, medicine, science, and technology. Understanding its properties helps us use it safely and effectively. The electromagnetic spectrum includes waves from radio to gamma rays, all traveling at the speed of light. Each type has unique properties and practical uses, from cooking to medical imaging. High-energy waves must be used carefully to avoid harmful effects.