Explain microwave communication and oven heating
Distinguish satellite television and mobile-phone carriers from absorbed microwave energy in food.
Section 3.3 · Electromagnetic spectrum
Exam scope and assessment notes
Core and Extended · Physics 0972, 2026–2028. Follow the selected spectrum or sound section. Diagrams illustrate stated ideal models and supplied data. Written practice is self-checked. Human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0972 has the same subject content as IGCSE 0625, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
Before you begin
- Locate the region in the electromagnetic spectrum.
- Distinguish a carrier from an output signal.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What travels between the electromagnetic source and detector?
What you will learn
- Explain the listed microwaves applications.
- Connect each apparatus to energy transfer or information detection.
Use a microwave carrier for communications
Satellite television links use microwaves between transmitting stations, satellites and receiving dishes. A mobile phone also communicates using microwave-frequency electromagnetic signals. The carrier represents information; it does not move a parcel of sound or picture material between devices.
Microwaves can pass through the atmosphere along suitable satellite paths. Real links depend on receiver alignment, obstacles and the selected band. A dish's role is to collect or direct the signal, not to slow it into an audible sound wave.
Distinguish energy absorption from a message
A microwave oven transfers energy to food by microwave absorption, producing heating. This is different from deliberately recovering encoded communication information. Food heating need not be uniform; thickness, composition and placement affect absorption and subsequent heat transfer.
The same region can serve different purposes because source power, arrangement and interaction matter. Calling a phone link 'microwave' does not make it an oven. This lesson explains applications, not procedures for opening an oven, altering its shielding or testing exposure.
Pause and explain
Which described microwave use deliberately heats food?
Worked example
Classify a satellite dish receiving television, a mobile phone link and food heating in an oven.
Show the worked solution
- The dish receives an information carrier.
- The phone exchanges encoded information.
- The oven transfers absorbed microwave energy to food.
Answer Satellite television and mobile phones communicate; the oven uses absorption for heating.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Identify the electromagnetic region used for a typical satellite television link.
Give me a hint
Recall the carrier linking station, satellite and receiving dish.
Compare my reasoning
- A transmitter sends encoded information.
- The satellite link uses microwaves.
- A receiving dish collects the signal.
Microwaves.
Look for these in your work
- Name the region.
- Distinguish the carrier from programme content.
Explain why a mobile phone link is not a travelling sound wave.
Give me a hint
Name the physical carrier and the reproduced output separately.
Compare my reasoning
- The phone represents the voice as signal information.
- Microwaves carry that information.
- A receiver creates local sound from it.
The carrier is electromagnetic; the voice is represented information.
Look for these in your work
- Name microwaves.
- Explain the conversion.
Two microwave arrangements carry a message and heat food. Why does the shared region not imply identical effects?
Give me a hint
Compare absorption, power and what the apparatus is designed to do.
Compare my reasoning
- One system recovers encoded information.
- The oven supplies absorbed energy for heating.
- The region name alone does not specify power or the arrangement.
Different powers, interactions and apparatus purposes give different applications.
Look for these in your work
- Separate energy transfer and information.
- Avoid inferring an effect from region alone.
Common mistakes
- Name both the region and its specific use.
- Explain the physical role rather than only naming apparatus.
- The listed application does not remove apparatus or exposure limits.
What can you explain now?
Are all microwaves applications identical processes?
Compare with the explanation
No.
The source, interaction and receiver determine whether energy or information is being used.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Connect microwaves to satellite television, mobile phones and food heating with the correct mechanism.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.