Electromagnetic Spectrum (continued)
Overview
Every time you make a call, stream a film or use wireless internet, invisible electromagnetic waves are carrying your data through the air and along glass fibres. Different parts of the spectrum suit different jobs, and modern communications choose each one for a reason.
In this lesson you will learn how satellites, mobile phones, Bluetooth and optical fibres each use a particular band of electromagnetic radiation, and why. You will also meet digital and analogue signals and understand the real advantages that make digital signalling the modern standard.
Objectives
- Know that communication with artificial satellites is mainly by microwaves: (a) s ome satellite phones use low orbit artificial satellites (b) some satellite phones and direct broadcast satellite television use geostationary satellites
- [Supplement] Know that many important systems of communications rely on electromagnetic radiation including: (a) m obile phones (cell phones) and wireless internet use microwaves because microwaves can penetrate some walls and only require a short aerial for transmission and reception (b) Bluetooth uses radio waves because radio waves pass through walls but the signal is weakened on doing so (c) optical fibres (visible light or infrared) are used for cable television and high-speed broadband because glass is transparent to visible light and some infrared; visible light and short wavelength infrared can carry high rates of data
- [Supplement] Know the difference between a digital and analogue signal
- [Supplement] Know that a sound can be transmitted as a digital or analogue signal
- [Supplement] Explain the benefits of digital signalling including increased rate of transmission of data and increased range due to accurate signal regeneration
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Lesson Evaluation
Congratulations on completing the lesson on Electromagnetic Spectrum (continued). Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- Communication with artificial satellites is mainly by: A. radio waves B. microwaves C. ultraviolet D. gamma rays Answer: B
- Bluetooth uses radio waves because they: A. travel fastest B. pass through walls C. cannot be blocked D. carry the most data Answer: B
- Optical fibres carry data using: A. microwaves B. radio waves C. visible light or infrared D. X-rays Answer: C
- A digital signal uses: A. a continuously varying value B. only two values, 0 and 1 C. analogue regeneration D. no carrier wave Answer: B
- A benefit of digital over analogue signalling is: A. it travels faster than light B. it can be regenerated accurately, increasing range C. it needs no aerial D. it cannot carry sound Answer: B
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