SCI SECOND QUARTER LESSON 1 G10

Electromagnetic Spectrum

Electromagnetic Waves

Waves that are created by the vibrations between an electric field and a magnetic field. These waves can travel through a vacuum at the speed of light.

Frequency (f)

The number of waves that pass a certain point in a specified amount of time. Measured in Hertz (Hz), where 1 Hz equals 1 wave per second.

Wavelength

The distance between one crest of a wave to the next crest or from one trough to the next trough. It determines the wave’s energy and frequency.

Non-Ionizing Radiation

Radiation that does not have enough energy to remove electrons from atoms or molecules. Examples include radio waves, microwaves, and visible light.

Ionizing Radiation

High-energy radiation capable of removing electrons from atoms and molecules, potentially causing damage. Examples include X-rays and gamma rays.

Radio Waves

A type of electromagnetic wave used in telecommunications and broadcasting. They have the longest wavelength in the electromagnetic spectrum.

Microwaves

Electromagnetic waves with shorter wavelengths than radio waves. They are used in cooking and satellite communications.

Infrared Radiation

A form of electromagnetic radiation with wavelengths longer than visible light but shorter than microwaves. It is felt as heat and is used in night vision technology.

Visible Light

• The portion of the electromagnetic spectrum that can be detected by the human eye. It ranges from violet (shorter wavelength) to red (longer wavelength).

Ultraviolet Radiation (UV)

• Radiation with shorter wavelengths than visible light. It can cause sunburns and is used for sterilizing medical equipment.

X-rays

• High-energy radiation that can penetrate most substances, used primarily in medical imaging and security screening.

Gamma RAYS

The highest energy form of electromagnetic radiation, emitted by radioactive substances. They can be used to treat cancer but can also cause severe biological damage.

Hans Christian Ørsted (1777–1851)

• Contribution: Ørsted discovered that an electric current creates a magnetic field.

• Significance: In 1820, he found that a compass needle was deflected when placed near a wire carrying an electric current. This discovery established the fundamental relationship between electricity and magnetism, showing that electricity produces magnetism.

• Impact: His findings were pivotal in the development of electromagnetism, which laid the groundwork for future discoveries.

Michael Faraday (1791–1867)

• Contribution: Faraday discovered electromagnetic induction and established that a changing magnetic field produces an electric current.

• Significance: In 1831, he showed that moving a magnet through a coil of wire could induce an electric current in the wire. This phenomenon is the basis for how generators and transformers work.

• Impact: Faraday's law of induction is a key principle in electromagnetism and is essential for technologies that produce and use electricity, such as electric motors and power generation.

James Clerk Maxwell (1831–1899)

• Contribution: Maxwell formulated the Maxwell equations, which describe the fundamental relationships between electric and magnetic fields and how they interact to produce electromagnetic waves.

• Significance: Maxwell unified electricity, magnetism, and optics into a single theory of electromagnetism. His equations demonstrated that light is an electromagnetic wave and travel at the speed of light.

• Impact: Maxwell’s work laid the foundation for the development of modern physics, including the theory of electromagnetic radiation and the later development of quantum mechanics and relativity.

Heinrich Hertz (1857–1894)

• Contribution: Hertz confirmed the existence of electromagnetic waves predicted by Maxwell by generating and detecting them in the laboratory.

• Significance: In 1887, Hertz demonstrated that radio waves (a form of electromagnetic radiation) behave like light waves and can be reflected, refracted, and diffracted, just like light.

• Impact: Hertz's work verified Maxwell's theory and laid the foundation for the development of radio, television, and wireless communication.

André-Marie Ampère (1775–1836)

• Contribution: Ampère is known for formulating Ampère's Law, which describes the relationship between electric current and the magnetic field it produces.

• Significance: He is considered one of the founders of electromagnetism and showed that electric currents create magnetic fields. He also contributed to the concept of electromagnetic force.

• Impact: Ampère's work is fundamental in the development of electrical circuits, and the ampere (unit of electric current) is named in his honor.

André-Marie Ampère (1775–1836)

• Contribution: Ampère also helped develop the idea of the electrodynamic theory, which describes the interaction between electric currents and magnetic fields.

• Significance: His theory of electromagnetic force formed the basis of modern electrodynamics, providing a theoretical foundation for the motors and generators that are central to modern electrical systems.

• Impact: Ampère's work is still crucial to the understanding of electrical engineering, particularly in circuit theory and the development of electrical machinery.

1. Radio Waves:

• Communication: Radio waves are widely used in television, radio broadcasting, and cellular communication (mobile phones, Wi-Fi, Bluetooth).

• Navigation: They are used in GPS systems, aviation, and maritime communication.

• Medical: MRI (Magnetic Resonance Imaging) uses radio waves to produce detailed images of organs and tissues inside the body.

Microwaves

• Cooking: Microwave ovens use microwaves to heat food quickly by exciting water molecules.

• Communication: Used in satellite communication, Wi-Fi, and cellular networks.

• Radar Systems: Microwaves are used in radar to detect objects and measure their speed (e.g., weather radar and military radar)

Radar

• Weather Forecasting: Radar is used in weather stations to detect storms, rain, and other atmospheric conditions.

• Air Traffic Control: It helps track airplanes, providing positioning information for safe navigation.

• Military: Military radar systems are used for surveillance, target detection, and navigation in hostile environments.

Infrared

• Thermal Imaging: Infrared cameras are used to see heat patterns, which helps in night vision, search and rescue operations, and detecting heat leaks in buildings.

• Remote Controls: Infrared sensors are used in devices like TV remote controls and smartphone gesture recognition.

• Medical: Infrared therapy is used for treating muscle injuries and promoting circulation.

Visible Light

• Human Vision: Visible light is the portion of the electromagnetic spectrum visible to the human eye, allowing us to see the world around us.

• Photography and Filming: Cameras and video recording devices use visible light to capture images and videos.

• Displays: LEDs, LCD screens, and OLED screens use visible light for displays in smartphones, televisions, and computers.

Ultraviolet (UV)

• Sterilization: UV light is used to disinfect water, air, and surfaces (e.g., in UV sterilization lamps in medical and laboratory environments).

• Medical: UV radiation is used in treating skin conditions like psoriasis and in Vitamin D production when exposed to sunlight.

• Forensics: UV light helps forensic experts detect substances like blood, fingerprints, and other trace evidence.

X-rays

• Medical Imaging: X-rays are widely used in radiography (e.g., X-ray machines) to examine the internal structures of the body, such as bones and organs.

• Security: Airport security scanners use X-rays to inspect luggage for dangerous objects.

• Industrial Testing: X-ray inspection is used to check materials for structural integrity in industries like aerospace, automotive, and construction.

Gamma Rays

• Cancer Treatment: Gamma rays are used in radiation therapy to kill or damage cancer cells in a process known as radiotherapy.

• Sterilization: Gamma radiation is used to sterilize medical equipment, food, and other items by killing bacteria, viruses, and other pathogens.

• Nuclear Industry: Gamma rays are used in nuclear reactors and nuclear medicine for diagnostic imaging (e.g., PET scans).

• Astronomy: Gamma-ray telescopes are used to study high-energy phenomena in space, like black holes and supernova explosions.