Explanation

• Wavelength is the distance between two successive crests or two successive troughs in a transverse wave.
• It represents one complete cycle of a wave.

Additional information:

• Symbol used: λ (Lambda)
• SI unit: meter (m)
• Wave formula: v = fλ
• Example wavelength values: 1 m, 0.5 m, 10 cm, 500 nm, 700 nm
• Visible light wavelength range: ~400 nm – 700 nm

Last verified on 12-03-2026

Explanation

• LED (Light Emitting Diode) is a semiconductor device that emits light when electric current passes through it.
• It is widely used in lighting, displays, electronic indicators, and screens.

Additional information:

• Energy efficiency: Up to 90% more efficient than traditional bulbs
  First discovery: H. J. Round – 1907
  Early research: Oleg Losev – 1927
  Practical LED development: James R. Biard – 1961
  First commercial production: October 1962 (Nick Holonyak)

Last verified on 12-03-2026

Explanation

• An optical instrument used to measure the properties of visible light is called a Spectroscope.
• It analyzes the composition and properties of materials based on the light they emit or absorb.
• It helping us understand the physical and chemical properties of objects in the universe.

Last verified on 12-03-2026

Explanation

• The telescope was first used for astronomical observations in the early 17th century.
• Galileo Galilei first used an improved telescope in 1609 to observe planets like Jupiter, Saturn, and Venus.
• He discovered four large moons of Jupiter (Io, Europa, Ganymede, and Callisto).

Last verified on 11-03-2026

Explanation

• The molecular structure (double-helix model) of DNA was proposed in 1953.
• This model explained how DNA replicates and carries genetic information in living organisms.
• The discovery was made by James Watson and Francis Crick, two molecular biologists.

Last verified on 11-03-2026

Explanation

• A chemical reaction that releases heat energy to the surroundings is called an Exothermic Reaction.
• In such reactions, energy is produced in the form of heat, light, or flames.
• Examples include combustion of fuel, respiration, and neutralization reactions.

Additional information:

• An endothermic reaction, which absorbs heat from the surroundings.

Last verified on 11-03-2026

Explanation

• The branch of chemistry that studies heat energy released or absorbed during chemical reactions is called Thermochemistry.
• It explains how heat changes occur during reactions such as combustion, neutralization, and dissolution.
• It deals with concepts like enthalpy change (ΔH), exothermic reactions, and endothermic reactions.

Last verified on 11-03-2026

Explanation

• A Telescope is an optical instrument used to observe distant objects such as stars, planets, and galaxies.
• It collects and magnifies light or other forms of electromagnetic radiation.
• The term “telescope” was coined in 1611 by the Greek mathematician Giovanni Demisiani.

Last verified on 10-03-2026

Explanation

• Antoine Lavoisier, a French chemist, is credited with discovering the law of conservation of mass in 1789 (1785).
• He demonstrated that matter cannot be created or destroyed in a chemical reaction, only transformed from one substance to another.

Last verified on 10-03-2026

Explanation

• The nervous system is the body system that controls and coordinates the functions of all other organ systems.
• It allowing for integration and regulation of various bodily functions.
• It consists of the brain, spinal cord, nerves, and sensory organs.

Last verified on 09-03-2026