GCSE Physics Revision "Uses of EM waves"

Summary

This video explains the uses of different types of electromagnetic waves, highlighting key examples from the specification. It covers radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays. Each section describes why certain electromagnetic waves are suitable for their respective uses, such as radio and TV signal transmission, satellite communication, heating food, fiber optic communication, and medical imaging. The video also touches on the risks associated with ultraviolet rays, including skin cancer. Viewers are encouraged to explore related questions in a workbook provided.

Takeaways

• 📡 Radio waves are used to transmit radio and terrestrial TV signals because they can travel long distances before being absorbed.
• 📶 Longer wavelength radio waves can diffract between hills and reflect off the ionosphere to travel very long distances.
• 🔥 Microwaves are used for heating food as water molecules absorb microwave energy, raising the temperature of the food.
• 🛰️ Microwaves are also used to communicate with satellites because they can pass through Earth's atmosphere without being reflected or refracted.
• 🌡️ Infrared is emitted by electrical heaters and used in ovens because it's easily absorbed by the surfaces of objects, making them warmer.
• 📷 Infrared is also used in cameras to check for heat loss in buildings.
• 💡 Visible light is crucial for communication via fiber optics, which transmit information through light pulses.
• 💡 Ultraviolet light is used in energy-efficient light bulbs as it carries more energy and is converted into visible light.
• 🌞 Ultraviolet is also used in tanning beds, though it increases the risk of skin cancer and premature aging.
• 🩻 X-rays and gamma rays are used for medical imaging (visualizing bones and detecting cancers) and treatments (like cancer therapy) due to their high penetrability.

Q & A

What are the primary uses of radio waves as mentioned in the video?

Radio waves are used to transmit radio signals and terrestrial TV signals. They are ideal because they can travel long distances before being absorbed by objects like buildings and trees. Additionally, longer wavelength radio waves can diffract, allowing them to spread out between hills.

Why are microwaves suitable for heating food?

Microwaves are suitable for heating food because water molecules in food absorb the energy from microwaves, which increases the temperature of the food.

How do microwaves aid in communication with satellites?

Microwaves can pass through the Earth's atmosphere without being reflected or refracted, making them ideal for communication with satellites in space.

What are the common uses of infrared radiation?

Infrared radiation is used in electrical heaters, cooking food in ovens, and infrared cameras. It is absorbed by the surface of objects, which causes them to warm up, making infrared useful for heating and detecting heat losses in buildings.

How is visible light used in communication?

Visible light is used in communication through fiber optics. Optical fibers transmit pulses of light to carry information such as telephone and cable TV signals, benefiting from the short wavelength of visible light, which allows it to carry a large amount of information.

Why is ultraviolet light used in energy-efficient light bulbs?

Ultraviolet light is used in energy-efficient light bulbs because it has a short wavelength and carries more energy than visible light. The ultraviolet energy is absorbed by the internal surface of the bulb and converted into visible light, requiring less energy compared to traditional light bulbs.

What are the risks associated with ultraviolet (UV) radiation?

Ultraviolet radiation increases the risk of skin cancer and causes premature skin aging, particularly when used in tanning beds.

How are x-rays used in medical imaging?

X-rays are used to visualize broken bones in medical imaging. They pass easily through body tissue but are absorbed by bones, allowing bones to be seen on x-ray images.

What is a medical application of gamma rays?

Gamma rays are used in medical imaging to detect cancers. Additionally, both x-rays and gamma rays are used for medical treatments, such as treating cancer.

What characteristic makes both x-rays and gamma rays suitable for medical use?

Both x-rays and gamma rays are highly penetrative, meaning they can easily pass through body tissue, which makes them suitable for medical imaging and treatment applications.

Outlines

00:00

📡 Introduction to Electromagnetic Waves

The video introduces the topic of electromagnetic waves, emphasizing the need to understand their uses. For higher-level students, the focus is on explaining why specific waves are suitable for their applications. While electromagnetic waves have many uses, this lesson will focus on examples explicitly stated in the specification.

📻 Uses of Radio Waves

Radio waves are used to transmit radio and terrestrial TV signals, which are received via an aerial (like Freeview). They are effective for long-distance transmission since they can travel without being absorbed by objects like buildings and trees. Long-wavelength radio waves can also diffract around hills. Additionally, radio waves reflect off the ionosphere, enabling them to travel great distances across the Earth.

🍽️ Uses of Microwaves

Microwaves are primarily used for heating food because water molecules in food absorb microwave energy, raising the temperature. Microwaves are also used for satellite communication since they can pass through the Earth's atmosphere without significant reflection or refraction.

🔥 Uses of Infrared

Infrared radiation is emitted by electrical heaters and used for cooking food in ovens. This is because infrared energy is easily absorbed by the surface of objects, making them warmer. Infrared is also used in infrared cameras to detect heat loss in buildings.

💡 Uses of Visible Light

Visible light is crucial for communication via fiber optics, where pulses of light are transmitted through thin glass strands to carry information. Optical fibers are used for telephone and cable TV signals. The short wavelength of visible light allows it to carry large amounts of data.

☀️ Uses of Ultraviolet Light

Ultraviolet light is used in energy-efficient lightbulbs because its short wavelength allows it to carry more energy, which is converted into visible light by the bulb's internal surface. Ultraviolet light is also used in sun tanning but comes with risks such as skin cancer and premature aging.

🩻 Uses of X-rays and Gamma Rays

X-rays and gamma rays are used in medical imaging and treatment. X-rays help visualize bones due to their ability to pass through body tissues but not bones. Gamma rays are used to detect cancers. Both are also used in cancer treatments due to their high penetrative abilities.

Keywords

💡Electromagnetic waves

Electromagnetic waves are forms of energy that travel through space at the speed of light. The video explains their various uses, from radio transmission to medical imaging. These waves include radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays, each with different properties and applications.

💡Radio waves

Radio waves are a type of electromagnetic wave used for transmitting radio and terrestrial TV signals. They are suitable for this purpose because they can travel long distances without being absorbed by obstacles like buildings and trees. The video highlights how radio waves can reflect off the ionosphere to travel vast distances across Earth.

💡Microwaves

Microwaves are electromagnetic waves used in both cooking and communication with satellites. The video explains that microwaves heat food by causing water molecules in the food to absorb energy, raising its temperature. Additionally, microwaves are able to pass through Earth's atmosphere, making them ideal for satellite communication.

💡Infrared

Infrared waves are emitted by objects like electrical heaters and are absorbed by surfaces, making them useful for heating spaces and cooking. Infrared is also used in devices like infrared cameras, which detect heat loss in buildings. The video highlights its application in practical heating and imaging technologies.

💡Visible light

Visible light is the part of the electromagnetic spectrum that is detectable by the human eye. It is used in communication via fiber optics, where light pulses transmit information over long distances. The video mentions how visible light's short wavelength allows it to carry a large amount of information, making it crucial for technologies like telephone and cable TV signals.

💡Ultraviolet

Ultraviolet (UV) light has a shorter wavelength and higher energy than visible light. It is used in energy-efficient light bulbs, where it is absorbed and converted to visible light. UV light is also used for tanning, but the video warns of the risks associated with UV exposure, including skin cancer and premature aging.

💡X-rays

X-rays are high-energy electromagnetic waves that can pass through soft tissue but are absorbed by bones. This makes them useful for medical imaging, such as detecting broken bones. The video also mentions that X-rays can be used in cancer treatments due to their penetrative properties.

💡Gamma rays

Gamma rays are the highest-energy electromagnetic waves, often used in medical imaging and cancer treatment. The video highlights their ability to detect cancers and their use in radiation therapy, where their penetrative power allows them to target deep tissues.

💡Ionosphere

The ionosphere is a layer of charged particles in Earth’s atmosphere that reflects certain types of radio waves, enabling them to travel long distances. The video mentions how this reflection allows radio waves to be transmitted over vast areas, such as around the Earth.

💡Diffraction

Diffraction refers to the bending of waves around obstacles, such as when longer-wavelength radio waves spread out between hills. While the video notes that diffraction is not explicitly part of the exam specification, it explains that this property helps radio waves to travel in complex terrains.

Highlights

Introduction to electromagnetic waves and their uses, with a focus on specific examples mentioned in the specification.

Radio waves are used to transmit radio and terrestrial TV signals because they can travel long distances before being absorbed.

Longer wavelength radio waves can diffract between hills, allowing them to spread out and travel further.

Radio waves can reflect off the ionosphere, a layer of charged particles, allowing long-distance communication around the Earth.

Microwaves are used to heat food because water molecules absorb their energy, causing the temperature of the food to increase.

Microwaves are also used for satellite communication since they can pass through the Earth's atmosphere without reflection or refraction.

Infrared is used in electrical heaters and ovens because its energy is easily absorbed by the surface of objects, making them warmer.

Infrared cameras are used to detect heat losses in buildings.

Visible light is used for communication in fiber optics, where light pulses transmit information through thin strands of glass.

Because of its short wavelength, visible light can carry a large amount of information, making it ideal for transmitting telephone and cable TV signals.

Ultraviolet light is used in energy-efficient light bulbs as it carries more energy than visible light and can be converted to visible light inside the bulb.

Ultraviolet is also used in sun tanning beds, but it increases the risk of skin cancer and causes premature skin aging.

X-rays are used for medical imaging, particularly to visualize broken bones because they pass through body tissue but are absorbed by bones.

Gamma rays are used in medical imaging to detect cancers and also in medical treatments such as cancer therapy.

Both X-rays and gamma rays are highly penetrative, making them suitable for medical imaging and treatment purposes.

Transcripts

[Music]

hi and welcome back to three slice

lessons cold okay by the end of this

video you should be able to describe the

uses of electromagnetic waves and if

you're a higher tiered student then you

need to be able to explain why each type

of electromagnetic wave is suitable for

its users now I should point out that

electromagnetic waves have got hundreds

of uses the ones I'm showing you in this

video are directly stated in a

specification so you need to learn these

specific examples we're going to start

with radio waves radio waves are used to

transmit both radio signals and

terrestrial TV signals remember the

terrestrial TV is not satellite or cable

TV terrestrial TV is received using an

aerial for example free view now radio

waves are used because they can travel

long distances before being absorbed for

example by buildings and trees longer

wavelength radio waves can also spread

out between hills on that's called

diffraction I should point out that the

word the function is not on your

specification radio waves can also

reflect off a layer of charged particles

in the atmosphere and that's called the

ionosphere this allows us to send radio

waves very long distances around the

Earth okay let's look at microwaves

firstly microwaves are used for heating

food that's because most foods contain a

lot of water molecules and water

molecules absorb the energy of

microwaves the energy causes the

temperature of the food to increase

secondly microwaves are used to

communicate with satellites in space and

that's because microwaves can pass

through the Earth's atmosphere without

being reflected or refracted okay we're

gonna look now at infrared infrared is

emitted by electrical heaters and it's

also used to cook food in ovens that's

because the energy of infrared is easily

absorbed by the surface of objects for

example the infrared from a heater is

absorbed by objects in the room and this

makes a room warmer infrared is also

used in infrared cameras for example to

check buildings for heat losses let's

look now at visible light

a really important use of visible light

is communication using fiber optics I'm

showing you here a bunch of optical

fibers optical fibers are very thin

strands of glass we can transmit pulses

of light down these fibers and use these

courses to carry information optical

fibers are used to carry telephone and

cable TV signals now because visible

light has a short wavelength it can

carry a great deal of information okay

the next electromagnetic wave is

ultraviolet now a really important use

of ultraviolet is an energy-efficient

lightbulbs such as this one ultraviolet

light is created inside the bulb not

because ultraviolet has a short

wavelength it carries more energy than

visible light the energy of the

ultraviolet is absorbed by the internal

surface of the bulb and it's converted

to visible light this requires much less

energy than a normal light bulb another

use of ultraviolet is in Sun tanning for

example using a tanning bed such as this

one however remember that ultraviolet

increases the risk of skin cancer and it

causes premature skin aging okay let's

finish now by looking at x-rays and

gamma rays

both x-rays and gamma rays are used for

medical imaging for example x-rays can

be used to visualize broken bones gamma

rays are used to detect cancers and we

saw that in the videos on radioactivity

both x-rays and gamma rays are very

penetrative in other words they can pass

easily through body tissue

however x-rays are absorbed by bones

which is why we can see them on x-ray

images both x-rays and gamma rays can

also be used in medical treatments for

example to treat cancer remember you'll

find plenty of questions on the uses of

the electromagnetic spectrum

in my vision workbook and you can get

that by clicking on the link above

[Music]