Explanation

• Alpha particles are compact clusters of two protons and two neutrons.
• They are identical to the nucleus of a helium-4 atom.
• Alpha particles carry a +2 positive charge.
• They have high ionizing power but low penetrating power.
• A sheet of paper or human skin can stop alpha particles.

Last verified on 07-06-2025

Explanation

• Fission is the process in which a heavy atomic nucleus splits into two or more smaller nuclei, releasing a large amount of energy.
• It usually occurs when a heavy nucleus, such as Uranium-235 or Plutonium-239, absorbs a neutron.
• The process also releases additional neutrons, which can start a chain reaction.
• Nuclear fission is used in nuclear power plants and atomic bombs.

Last verified on 07-07-2026

Explanation

• Albert Einstein explained the Photoelectric Effect in 1905 by proposing that light consists of tiny particles called photons.
• He showed that electrons are emitted from a metal surface when light of sufficient frequency falls on it.
• His explanation supported Quantum Theory.
• Einstein received the Nobel Prize in Physics in 1921 for this discovery.

Last verified on 06-07-2026

Explanation

• Gravitational force is the fundamental force that attracts any two objects with mass toward each other.
• It was explained by Isaac Newton through the Law of Universal Gravitation.
• Gravity keeps planets in orbit around the Sun and causes objects to fall toward the Earth.

Last verified on 06-07-2026

Explanation

• 1 Nanometer (nm) = 10⁻⁹ m

Additional information:

• 1 Kilometer (km) = 10³ m
• 1 Meter (m) = 10⁰ m
• 1 Millimeter (mm) = 10⁻³ m
• 1 Micrometer (µm) = 10⁻⁶ m

Last verified on 06-07-2026