Bihar Board Class 10 · Social Science · Matric exam 2027
Chapter 5: Alternative Communication during Disaster — notes
The chapter’s 6 parts in the book’s order — the first idea of each and the points Medha Ma’am writes on the board — and the summary at the end. The full lesson and a check question for each part are in the app.
1. Why normal communication breaks down during disaster
Okay, so — disasters keep happening on earth, small ones and big ones.
- • Reasons for disruption:
- • (i) Breakage in cable
- • (ii) Disruption in electricity supply
- • (iii) Destruction of communication buildings/instruments
- • (iv) Damage to transmission tower
- • Example: Kosi embankment breach, 2nd August 2008
2. The Kosi flood: what happened when communication was lost
Okay, so let's look at what happened near Kusha during the Kosi flood.
- • Kosi embankment damage effects:
- • 16 districts, 92 blocks, 1598 villages affected
- • 27 lakh people rendered homeless
- • 1.06 lakh hectares of standing crops damaged
- • Most popular communication: Public telephone (PSTN)
- • PSTN carries: sound, Fax, Data
3. Even normal networks get overloaded in a disaster
Okay, so even the normal telephone service isn't safe during a disaster.
- • Disasters affecting telephones: earthquake, cyclone, flood, Tsunami, landslides
- • Main cause of telephone failure: power failure
- • Damaged towers affect police/civil wireless network too
- • PSTN full capacity: only 5% telephones can work at a time
- • In crisis: network overburdened, may totally fail
4. Radio Communication as an alternative means
Okay, so let's talk about another alternative means of communication — radio communication.
- • Radio waves: electromagnetic, sent through Antenna
- • Low, High, Extremely High frequency waves
- • High frequency -> distant places
- • Very high frequency -> short distance (5 to 50 km)
- • Extremely high frequency -> hand wireless (e.g., walkie-talkie)
5. Amateur or HAM Radio
Okay, so let's talk about a very special kind of radio — Amateur radio.
- • HAM radio = Amateur radio
- • No basic infrastructure needed
- • Used for: research, education, personal projects
- • Energy source: generator or batteries
- • India: almost 15,000 license holder operators
- • Example: Sandeep Barua contacted Port Blair
6. Satellite Communication
Okay, so let's talk about satellite communication.
- • INSAT: television, meteorology, disaster warnings
- • I.R.S.: search and management of resources
- • Set com: satellite based communication
- • Set phone: satellite based phone terminal
- • Transponder: receives, spreads, resends signals to earth
- • Satellite phone: most used, most reliable during disaster
Summary
Okay, so let's quickly go over what we learned today. See, disasters like flood, drought, earthquake, Tsunami, cyclone, landslide, avalanche and cold wave — they disrupt our normal communication system. Cables break, power fails, buildings get destroyed, and transmission towers get damaged. Remember the Kosi embankment flood of 2008? That left 27 lakh people homeless. Now, even the popular PSTN telephone network struggles during such times. Only 5 percent of telephones can work at full capacity, so the network gets overburdened and fails exactly when we need it most. Then we looked at three alternative means of communication. First, Radio Communication — this uses electromagnetic waves of different frequencies, sent through an Antenna. Second, Amateur or HAM Radio. This one's non-commercial, needs no big infrastructure, and runs on generators or batteries. It proved most effective during disasters — Sandeep Barua's work during a crisis showed us that. And third, Satellite Communication. This uses INSAT, I.R.S., set com, set phone and Transponders. It's the most reliable system, because it stays undamaged by disasters happening on earth. In fact, the satellite phone is the most used tool in disaster management. So, tell me — out of these three, which one do you think needs the least setup on the ground?
AskMedha · Medha Ma’am — Bihar Board Class 10 Social Science, Chapter 5. Written from the textbook, checked twice.
Questions parents and students ask
- How do I get the "Alternative Communication during Disaster" notes as a PDF?
- Press "Save as PDF" — the phone’s print sheet opens; choose "Save as PDF" there. The PDF holds the notes only.
- Where are these notes written from?
- From the chapter’s own textbook text, part by part, in the book’s own terms; a second, independent model then checked every part against the book. The full lesson, a check question for each part and the practice are in the AskMedha app.
The same preparation, with Medha Ma’am — on your phone
Every question of every chapter with its model answer, practice questions in the board’s own shapes, 60 minutes of class a day, written answers marked, a test every Sunday and a WhatsApp report to parents.
Medha Ma’am is an AI teacher, not a live tutor. Every answer is checked twice; a person takes responsibility.