Process of Respiration

Process of Respiration

Lesson 6.3.1

Using Electromagnetic Waves to Communicate

Advantage of Electromagnetic Waves

Electromagnetic waves carry communications long distances through space at a very fast speed.

Cellphones

Cellphones send and receive microwaves to communicate with an antenna at a base station. Base stations provide service to a limited area, and it takes many base station(s) to provide coverage to a city. Information is sent between base stations using fiber-optic cables

Wi-Fi Devices

A fiber-optic cable uses infrared light to transmit signals to a router, which converts the signals into EM waves that transmit information to client devices, such as cellphones and computers.

Collecting Information

Scanners collect information and examine objects. Computer scanners copies images and texts using reflected visible light waves. Bar code scanners read black and white patterns using red light. Baggage security scanners make images using transmitted and absorbed x-rays. An X-ray machine sends X-rays through a patient's body. Denser parts of the body, such as bones, absorb more X-rays and show up as a lighter color on the X-ray image.

The Doppler Effect

Moving towards the observer, the waves seem to have higher frequency. Moving away from the observer, the waves seem to have lower frequency.

Solar Power

A semiconductor absorbs photons in sunlight. Then electrons are freed and flow through the device. Finally, electrons produce electricity as they flow through metal contacts.

Multiple Select

Which two characteristics make electromagnetic waves effective in communication?

• They move faster through matter than through space.

• They carry information very quickly.

• They do not require a medium to carry information.

• They carry more energy than visible light.

Multiple Choice

Why are networks of cables not used to send information from a remote control to a television?

• Infrared radiation cannot travel through cables.

• Microwaves cannot travel through cables.

• The information needs to travel only a short distance.

• Cables slow down the speed at which information is communicated.

Multiple Select

Which three applications use technologies that apply the Doppler effect?

• Weather forecasting

• Pest control

• Air-traffic control

• Building inspection

Multiple Select

What are two ways in which ultrasound technology produces images?

• By measuring the time it takes for reflected sound waves to be detected

• By the absorption of sound waves in the body

• By detecting the frequencies of emitted sound waves

• By using sound in frequencies that reflect off body tissues

Multiple Choice

Why does a patient receive more radiation from a CT scan than from having an X-ray image made?

• The X-rays are more powerful in a CT scan.

• Higher-frequency rays are used in a CT scan.

• Fewer X-rays are reflected in a CT scan.

• A CT scan involves multiple X-ray images.

Multiple Choice

By what process do electromagnetic waves release electrons from the materials they contact?

• Absorption of electromagnetic waves

• Reflection of electromagnetic waves

• Flow of electrons from negative to positive poles

• The photoelectric effect