This is Day 59 | 90 Days RAS Mains 2025 Answer Writing, We will cover the whole RAS Mains 2025 with this 90-day answer writing program
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GS Answer Writing – Physics in everyday life | Gravitation | The human eye and Defects | Heat । Paragraph
Ans 1. Accommodation,near and far points:
The eye lens can modify its curvature to some extent with the assistance of the ciliary muscles. This alteration in curvature enables the eye lens to adjust its focal length. The ability of the eye lens to adjust its focal length is called accommodation.
- The near point, where objects can be seen most distinctly without strain, is about 25 cm for a young adult with normal vision.
- The far point, the farthest distance at which objects can be seen clearly, is considered to be infinity for a normal eye.
Thus, a normal eye can see objects clearly between 25 cm and infinity.
Ans 2.
Heating effect of electric current
The heating effect of electric current, also known as Joule heating, occurs when electrical energy is converted into heat energy due to the resistance in a circuit. This phenomenon is particularly prominent in circuits composed solely of resistive elements, where the energy from the source is entirely dissipated as heat.
Practical applications of the heating effect of electric current include:
- Electric Heating Devices: Household appliances like irons, toasters, ovens, kettles, and heaters use Joule heating, converting electric energy to heat for tasks like cooking and heating.
- Electric Bulbs: While the majority of the energy consumed by the filament is converted into heat, a portion is radiated as visible light, fulfilling the bulb’s purpose of illumination.
- Fuses in Electric Circuits: When excessive current flows through a circuit, the fuse wire heats up due to Joule heating, melts, and breaks the circuit, preventing damage.
Ans3.
Lightning Thunderstorms
- Thunderstorms are complex atmospheric phenomena characterized by the rapid upward movement of warm, moist air and the formation of cumulonimbus clouds. Strong updrafts within the cloud carry water droplets to higher altitudes, where they freeze and form ice crystals.
- Within clouds, ice particles undergo growth, collision, fracture, and separation, leading to the acquisition of positive charges by smaller particles and negative charges by larger ones. These charged particles become separated by updrafts and gravity, establishing a dipole structure with the upper portion of the cloud positively charged and the middle negatively charged. During thunderstorm development, the ground becomes positively charged
- cosmic and radioactive radiations ionize air, making it weakly electrically conductive. The separation of charges within the cloud and between the cloud and ground generates tremendous electrical potential, reaching millions of volts. Eventually, the electrical resistance in the air breaks down, initiating lightning flashes with currents of thousands of amperes and electric fields of about 10^5 V/m.
Ans4.
Foam insulation on the ceiling Concrete roofs tend to become excessively hot during summer days due to the material’s significant thermal conductivity. To counteract this, people often choose to apply a layer of earth or foam insulation on the ceiling. This insulation effectively prohibits heat transfer from the roof into the interior of the house, helping to maintain cooler indoor temperatures.
Paper 4 (Comprehension part) – paragraph
Day 59 | 90 Days RAS Mains 2025 Answer Writing
Day 59 | 90 Days RAS Mains 2025 Answer Writing
