Explanation

• Solar plates consist of photovoltaic (PV) cells.
• PV cells convert sunlight directly into electrical energy.
• These cells work on the photovoltaic effect. 
• They are usually made of semiconductor materials like silicon.

Additional information:

• Discovered photovoltaic effect: 1839 by Edmond Becquerel

Common types of solar cells:

1. Monocrystalline silicon cells
2. Polycrystalline silicon cells
3. Thin-film solar cells

Last verified on 23-06-2026

Explanation

• Lead pencil is made up of graphite.
• Graphite is a form (allotrope) of carbon.
• It is soft and leaves marks on paper easily.
• It is used in pencils because of its slippery layered structure.
• Despite the name “lead pencil,” it contains no real lead.
• Graphite was named by Abraham Gottlob Werner in 1789.

Last verified on 21-06-2026

Explanation

• Chronometer is a highly precise time-measuring instrument.
• It is often used in navigation and scientific experiments.
• It is designed to measure time accurately, even under varying conditions.
• Chronometers played a key role in determining longitude at sea.

Last verified on 03-04-2026

Explanation

• Normal blood pressure is 120/80 mmHg.
• High-normal: 130–139 mmHg, High: >140 mmHg.
• mmHg means millimeters of mercury, the unit of pressure.
• Blood pressure is measured using a Sphygmomanometer.
• Maintaining normal BP is essential for heart and overall health.

Last verified on 02-04-2026

Explanation

• The normal resting heart rate of an adult human is about 70 beats per minute.
• It can vary depending on age, fitness, and health condition.

Additional information:

• Normal adult: 60–100 beats/min
• Athletes: 40–60 beats/min
• Children: 70–120 beats/min
• Infants: 100–160 beats/min

Last verified on 31-03-2026

Explanation

• Total planets: 8
• Inner planets: Mercury, Venus, Earth, Mars (4)
• Outer planets: Jupiter, Saturn, Uranus, Neptune (4)
• Pluto reclassified: 2006 (IAU decision)
• Largest planet: Jupiter
• Smallest planet: Mercury

Last verified on 01-04-2026

Explanation

• All plants move Anticlockwise around Sun.
• All plants move anticlockwise around their axis.
• Earth rotates its axis from West to East.

Last verified on 15-03-2026

Explanation

• The Moon's surface gravity is about 1/6th as powerful or about 1.6 meters per second.
• The Moon's surface gravity is weaker because it is far less massive than Earth.
• A body's surface gravity is proportional to its mass, but inversely proportional to the square of its radius.

Last verified on 13-03-2026

Explanation

• Pressure can be defined as the force acting per unit area.
• The unit of pressure is N/m² (Newton per square meter).
• It is also called Pascal (Pa).
• In SI base units kg⋅m−1⋅s−2
• Derivations from other quantities: p = F / A
• Dimension unit: M L^−1 T^-2.

Additional information 

The SI unit of energy/work is the joule (J)

Last updated on 09-03-2026

Explanation

• Sound waves are mechanical waves and need a medium to travel.
  • They travel fastest in solids, slower in liquids, and slowest in gases.
  • Solid particles are closely packed, allowing rapid vibration transfer.

Last verified on 04-02-2026