NCERT Formulas Class 10 Science Chapter 14 – Sources of Energy
NCERT Science • Class 10

Sources of Energy

Fuel Efficiency & Energy Laws

🔥 Characteristics of a Good Fuel

A good source of energy is defined by its efficiency and ease of use.

↔ Swipe to view calorific value logic

Calorific Value: Amount of heat produced by burning unit mass of fuel.

$$\text{Efficiency} \propto \frac{\text{Heat Produced}}{\text{Mass of Fuel}}$$

Ideal Fuel: High Calorific Value, Low Ignition Temperature, Eco-friendly.

💧 Conventional Energy Sources

Conversion of different forms of energy into electrical energy.

Hydro Power: Potential Energy $\rightarrow$ Kinetic Energy $\rightarrow$ Electrical Energy

$$\text{Potential Energy (P.E)} = mgh$$

Thermal Power: Chemical Energy (Coal) $\rightarrow$ Heat Energy $\rightarrow$ Mechanical Energy $\rightarrow$ Electricity

[Image of working of a thermal power plant] [Image of hydroelectric power plant diagram]
🐄 Biomass and Biogas (Gobar Gas)

Biogas is produced by the anaerobic decomposition of animal and plant wastes.

Main Components: Methane ($CH_4 \approx 75\%$), $CO_2$, $H_2$, $H_2S$.


Advantage: Leaves behind slurry rich in Nitrogen ($N$) and Phosphorus ($P$).

☀️ Solar Energy Devices

Devices that harness solar radiation directly.

Solar Constant: Amount of solar energy reaching 1 $m^2$ per second.

$$1.4 \text{ kJ/s/m}^2 \quad \text{or} \quad 1.4 \text{ kW/m}^2$$

Solar Cells: Convert Solar energy $\rightarrow$ Electricity using Silicon.

⚛️ Nuclear Energy Formulas

Energy released during nuclear fission or fusion based on mass defect.

Einstein’s Mass-Energy Relation: $$E = \Delta mc^2$$

($\Delta m = \text{mass defect}, c = 3 \times 10^8 \text{ m/s}$)


Nuclear Fission: Heavy nucleus ($U^{235}$) splits into lighter nuclei.

[Image of nuclear fission reaction chain]
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