Explanation

• Glass is an amorphous solid.
• It has no regular crystal structure, so its particles are arranged randomly.
• It softens gradually when heated.
• Glass is widely used in windows, bottles, lenses, and laboratory equipment.

Last verified on 07-07-2026

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

• The laws of magnetic induction were given by Michael Faraday.
• Faraday proposed these laws in 1831 after discovering electromagnetic induction.
• The laws explain that a changing magnetic field induces an electromotive force (EMF) in a conductor.
• These laws are the foundation of electric generators and transformers.

Last verified on 06-07-2026

Explanation

• Zero error is a Systematic error because it causes a consistent error in every measurement.
• It occurs when an instrument does not read zero even when no quantity is being measured.
• The same error is repeated in all readings unless corrected.
• Zero error may be positive or negative.
• It can be corrected by applying a zero correction.

Last verified on 06-07-2026

Explanation

• Convex lenses are known as Converging lenses.
• Because they bring parallel light rays to a single focal point.
• A convex lens is thicker at the center and thinner at the edges.
• It forms real and inverted images when the object is beyond the focal length.
• It can also produce a virtual, erect, and magnified image when the object is placed within the focal length.

Additional information:

• Concave lens is also called a diverging lens.

Last verified on 11-03-2026

Explanation

• Volt (V) is the SI unit of potential difference (voltage).
• Potential difference is the electrical force that causes current to flow through a conductor.
• It is measured using a voltmeter.
• The SI unit is named after Alessandro Volta.

Additional information:

• Electric Current: Ampere (A)
• Resistance: Ohm (Ω)
• Power: Watt (W)
• Charge: Coulomb (C)

Last verified on 03-06-2026

Explanation

• Radiation is the only mode of heat transfer that occurs through a vacuum.
• Radiation transfers heat through electromagnetic waves.
• So it does not need any material medium.
• The Sun's heat reaches the Earth through radiation.

Last verified on 06-07-2026