Explanation

• 1 hp = 746 W
• 1 hp = 0.746 kW
• 1 kW = 1.34 hp
• 1 W = 0.00134 hp
• Standard unit system: SI unit of power is Watt

Last verified on 23-06-2026

Explanation

• The efficiency of a diesel engine is about 30–40%.
• It means only this percentage of fuel energy is converted into useful work.
• The remaining energy is lost as heat, friction, and exhaust gases.
• Diesel engines are generally more efficient than petrol engines.

Last verified on 23-06-2026

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

• The audible range of a normal human ear is 20 Hz to 20,000 Hz (20 kHz).
• Sounds below this range are called infrasound,
• Sounds above it are called ultrasound. 
• Lower limit: 20 Hz (deep rumbles)
• Upper limit: 20,000 Hz (high-pitched squeaks)

Additional information

• Adult change: The upper limit often drops to 15,000–17,000 Hz as people get older. 
• Unit of frequency: Hertz (Hz)

Last updated 27-07-2026 by NA

Explanation

• Theory proposed by: Charles Darwin
• Book published: 1859
• Book name: On the Origin of Species
• Key concept: Natural Selection
• Voyage that inspired him: HMS Beagle expedition (1831–1836)

Last verified on 21-06-2026

Explanation

• Discoverer: Victor Hess
• Year: 1912
• Method: High-altitude balloon experiments
• Nobel Prize: 1936 (Physics)
• Field: Astrophysics / Space radiation

Last verified on 20-06-2026

Explanation

• Total standard zones: 24
• Earth rotation time: 24 hours
• Longitude per zone: 15 degrees
• Starting point: Greenwich (0°)
• It is used worldwide for time coordination.

Last verified on 14-06-2026

Explanation

• When a body moves upward, its height from the ground increases.
• Gravitational potential energy depends on height (P.E = mgh), so it increases as height increases.
• The increase in potential energy comes from the conversion of kinetic energy into potential energy.

Last verified on 18-06-2026

Explanation

• Picosecond (ps) = 10⁻¹² seconds
• SI prefix “pico” means 10⁻¹².
• 1 picosecond = one trillionth of a second.

Additional information:

• Microsecond (μs) = 10⁻⁶ seconds
• Nanosecond (ns) = 10⁻⁹ seconds
• Millisecond (ms) = 10⁻³ seconds
• Femtosecond (fs) = 10⁻¹⁵ seconds
• Attosecond (as) = 10⁻¹⁸ seconds
• Zeptosecond (zs) = 10⁻²¹ seconds
• Yoctosecond (ys) = 10⁻²⁴ seconds

Last verified on 17-06-2026

Explanation

• The dimension of viscosity is [ML⁻¹T⁻¹].
• Viscosity measures a fluid’s resistance to flow.
• Higher viscosity means thicker fluid (like honey).
• Lower viscosity means thinner fluid (like water).

Last verified on 17-06-2026