How technology supports life and society
Technology is a tool or method, together with the know-how to use it, that solves a problem. Food, light, moving things and keeping warm are needs of every family. Technology helps us meet them. We look at two big areas: growing living things and converting energy.
Growing crops, animals and fish: the right conditions
Every living thing has growing conditions, the things it needs to be healthy.
- Plants: sunlight, water, air, suitable temperature, soil with nutrients.
- Animals (cow, hen): clean water, enough feed, space, shade or warmth, and care when sick.
- Fish: clean water with enough oxygen, the right water temperature, and the right amount of feed.
Each factor has a good middle range. Too little or too much both hurt. Too little water makes a plant droop. Too much water rots the roots. In the 3D, only when all three sliders are near the middle does the plant grow best.
Planning and managing cultivation
Good growers do not just hope. They follow steps:
- Aim: choose what to grow and when (the season matters).
- Plan: choose seeds, space, water schedule and a calendar.
- Grow and manage: water, give light, remove weeds and pests, add manure.
- Check and record: measure height, count leaves, write it down.
- Harvest and improve: look at the result and fix problems next time.
Tools help: a moisture sensor tells how dry the soil is, a timer or pump waters automatically, and a greenhouse keeps heat and light steady. Machines save effort, but we must still look at the plant.
Energy conversion: electricity, motion and heat
Energy cannot be made or destroyed. It only changes form. A device that changes one form into another is an energy converter.
- Motor: electricity into motion (fan, mixer, toy car).
- Heater or iron: electricity into heat.
- Generator: motion into electricity (bicycle dynamo, power station).
- Bulb or LED: electricity into light.
No converter is perfect. A motor gives useful motion, but some energy turns into heat that is not useful. Efficiency = useful output ÷ input × 100 %. A motor with 100 J in and 70 J of useful motion is 70 % efficient. For more, see the lesson on energy transformations.
Mechanisms and circuits, and keeping them safe
A mechanism moves or changes force. Gears pass turning from one wheel to another. A small gear driving a big gear turns slower but with more pushing power. A lever and a pulley help to lift things with less effort.
A circuit is a closed path for electric current: battery, wire, switch and a load such as a motor. If the path is broken, nothing runs.
Safe use and care (maintenance): never touch switches with wet hands, use a fuse or MCB, switch off before cleaning, keep wires covered, oil moving parts, and check regularly for loose or hot parts. A regular check is cheaper than a repair.
Try it
Grow test at home (7 days). Sow 10 mung seeds in each of three cups: (A) water daily and kept near a window, (B) no water, (C) water daily but kept in a dark cupboard. Predict first, then measure the height every day and write it in a table. Which cup grows best? In the 3D, set the sliders the same way and check your prediction.
Feel the motor. Run a small table fan for 10 minutes and gently feel the motor housing. It is warm: that is wasted heat.
Key formulas and definitions
- Efficiency (%) = useful output ÷ input × 100
- Wasted energy = input − useful output
- Electrical energy (kWh) = power (kW) × time (h)
- Gear speed ratio: output speed = input speed × (teeth on driver ÷ teeth on driven)
- Germination % = seeds that sprouted ÷ seeds sown × 100
Worked examples
1. You sow 20 seeds and 16 sprout. What is the germination percentage?
16 ÷ 20 × 100 = 80 %.
2. A small motor takes 100 J of electrical energy and gives 70 J of useful motion. Find the efficiency and the wasted energy.
Efficiency = 70 ÷ 100 × 100 = 70 %. Wasted = 100 − 70 = 30 J (mostly heat).
3. A 60 W fan runs for 10 hours. How much energy does it use in kWh?
60 W = 0.06 kW. Energy = 0.06 × 10 = 0.6 kWh.
4. If electricity costs ₹7 per kWh, what does the fan in the last question cost?
0.6 × 7 = ₹4.20.
5. A gear with 10 teeth turns at 60 rpm and drives a gear with 30 teeth. How fast does the big gear turn?
Speed = 60 × (10 ÷ 30) = 20 rpm. It turns slower but pushes harder.
6. A soil sensor shows 15 % moisture. The plant needs at least 40 %. The pump gives 5 % per minute. How long should the pump run?
Needed rise = 40 − 15 = 25 %. Time = 25 ÷ 5 = 5 minutes.
Common mistakes
- Thinking more water or more heat is always better. Each condition has a good middle range.
- Trusting a machine without checking. Sensors can fail, so look at the plant too.
- Saying energy is "used up". It changes form, often into heat we cannot use.
- Touching a running motor, wires or sockets with wet hands. Always switch off first.