Explanation

• Wavelength is the distance between successive wave crests.
• SI unit: Meter (m)
• Commonly measured in: Nanometers (nm) and Angstroms (Å)
• 1 nm = 10⁻⁹ m
• 1 Å = 10⁻¹⁰ m = 0.1 nm
• Visible light: Approximately 400–700 nm

Last updated: 20-09-2026 by NA

Explanation

• Astrology studies the supposed influence of stars and planets on human affairs.
• Origin: Ancient Mesopotamia (modern Iraq).
• Developed by: Sumerians and Babylonians.
• Period: Around the 3rd–2nd millennia BCE.

Explanation

• Ice is less dense than water, so it floats.
• Archimedes’ Principle explains the buoyant force acting on floating ice.
• The buoyant force acts upward against gravity.
• Formula: FB = p Vg
• Key point: An object floats when buoyant force = its weight.

Explanation

Bernoulli’s principle is based on conservation of energy in flowing fluids.

P+1/2 ρv2+ρgh=constant

For airplane wings:

• P = Pressure
• ρ (rho) = Density of air
• v = Speed of air
• g = Gravitational acceleration
• h = Height
• Higher air speed → Lower pressure
• Lower air speed → Higher pressure
• Pressure difference between the upper and lower surfaces creates lift.
• Lift acts upward and helps the airplane fly

Explanation

• Earth’s gravity provides the force that keeps satellites in orbit.
• This gravitational force pulls the satellite toward Earth.
• The satellite’s forward motion makes it continuously fall around Earth rather than directly into it.
• Newton’s Law of Gravitation explains this gravitational attraction.