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NCERT Solutions for Class 7th Social Science Chapter 19 After the account of J.C. Bose and his inventions — THINK ABOUT IT

Book page 187 Updated on2026-09-19

Q1.
In the 1990s, mobile calls in India cost up to ₹17 per minute, with charges even for incoming calls. Today, India has some of the world’s cheapest mobile and internet rates. How do you think this became possible?
Answer

Mainly because the network grew enormously while the cost of building it was shared over far more users. A tower, a cable and a data centre cost roughly the same whether ten people use them or ten lakh; when the number of users rises, the cost carried by each user falls.

Using what this chapter itself tells us:

  • Huge numbers of users. By 2025 India had 1,160 million wireless telephone subscribers and nearly 900 million internet connections. In the 1990s a mobile phone was a rare object; today the same network is shared by more than a hundred crore connections.
  • The infrastructure was actually built. The chapter lists what is behind a call — cables, wireless devices, towers, satellites and data centres. Once fibre had been laid and towers put up across the country, each extra call added very little new cost.
  • The technology kept improving. Fig. 7.23 ends with 5G, cloud communication and AI-driven chat and voice services. Newer systems carry far more calls and data over the same equipment.
  • Competition between service providers. When several companies offer the same service, each must attract customers with lower rates — and the practice of charging for incoming calls disappeared altogether.
Cost of the network is mostly fixed; the number of users is very large
Cost carried by each user = total cost ÷ number of users
More users → smaller share each → lower price per minute
Why it happens: this is the same idea as a village bus. Running the bus costs about the same whether it carries five passengers or fifty — so the fare per passenger can fall sharply once the bus fills up. Communication networks work the same way, only on a national scale.
Q2.
In 2025, there are 1,160 million wireless telephone subscribers and nearly 900 million internet connections in India.
Answer

Read these two numbers together — they say that almost everyone is now reachable, but not everyone is yet online. The box gives them to think about, so let us work them out.

Wireless telephone subscribers = 1,160 million = 116 crore
Internet connections ≈ 900 million = 90 crore
Difference = 1,160 − 900 = 260 million ≈ 26 crore
Internet connections as a share of subscribers = 900 ÷ 1,160 ≈ 0.776 = about 78 per cent

What this tells us

  • India’s communication infrastructure — towers, fibre cables, satellites, data centres — is now reaching almost the whole country. Nothing on this scale existed when a call cost ₹17 a minute.
  • About four out of every five wireless connections also carry internet. So a phone in India today is usually a doorway to online classes, digital libraries, e-commerce and e-governance, not only to voice calls.
  • The gap of roughly 26 crore connections is the work still left. That is the gap Dr Kalam’s opening quotation is about — a developed India is one where rural areas have the same communication infrastructure as urban ones.
Tip: A “subscriber” or “connection” is not the same as a person. One person may hold two SIM cards, and one home connection may be shared by a whole family. So use these numbers to show the scale of the network, not to count people.
Q3.
Ask your family or people in the neighbourhood how they sent long-distance messages before mobile phones were introduced. What has been their experience of using the first telephone or mobile phone?
Answer

This is an interview activity, so the answer has to be collected, not looked up. Its aim is to turn Fig. 7.23’s timeline into living memory.

Method. Choose two or three people of different ages — a grandparent, a parent or neighbour in their forties, and someone in their twenties. Ask the same questions to each, write the answers in their own words, and note the person’s name and roughly which years they are describing.

Questions worth asking

  1. Before mobile phones, how did you send news to someone in another city or village? How many days did it take?
  2. Did you use letters, postcards, inland letters, telegrams, or a trunk call from a post office or PCO?
  3. What did it cost, and did you have to wait in a queue or book the call in advance?
  4. What was the first telephone or mobile phone you used, and in which year? How did it feel?
  5. What is the biggest difference you notice today?

What a good answer must contain: at least two named people, the method they used, a sense of time taken and cost, and one sentence in their own words. Finish with your own comparison to how you send a message today.

Sample answer: “I asked my grandmother, my father and my elder cousin.
My grandmother (about the 1970s): ‘We wrote inland letters. A letter to my brother in Chennai took six or seven days, and his reply took another week — so one exchange took a fortnight. For very urgent news we sent a telegram, and everyone in the house grew anxious when a telegram arrived, because it usually meant bad news.’
My father (about the 1990s): ‘There was one PCO in our market with a yellow board. I would stand in line, and on Sundays the rate was lower, so the queue was longest then. When we got our first mobile phone in 2001 it was a heavy Nokia, and we spoke fast because incoming calls were also charged.’
My cousin (2010s): ‘I have never posted a letter. I send voice notes and video calls.’
So in three generations one message has gone from a fortnight to a few seconds — exactly the change Fig. 7.23 shows from couriers and the telegraph to 5G and cloud communication.”
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