Explanation

• Sputnik-1 was launched by the USSR (Soviet Union) on 4 October 1957.
• It was the world's first artificial satellite, beginning of the Space Age.
• It started the Space Race between the Soviet Union and the United States.
• Launch Site: Baikonur Cosmodrome, Kazakhstan
• Weight: 83.6 kg
• Orbital Period: About 96 minutes

Last verified on 09-03-2026

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

• Boiling point of water: 100°C
• Freezing point of water: 0°C
• Standard atmospheric pressure: 1 atm (760 mmHg)
• 0°C = 32°F
• 100°C = 212°F

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

• Sound cannot travel through a vacuum because there are no particles to carry sound vibrations.
• Sound needs a medium such as a solid, liquid, or gas to travel.
• Since space is nearly a vacuum, sound cannot be heard there.
• The speed of sound in a vacuum is 0 m/s.

Additional information:

• Infrasound: Below 20 Hz
• Audible sound: 20 Hz – 20,000 Hz (20 kHz)
• Ultrasound: Above 20 kHz
• Speed of sound in air: 343 m/s
• Speed of sound in water: 1,481 m/s

Last verified on 07-06-2026

Explanation

• O₃ is the chemical formula of ozone gas.
• Ozone is an allotrope of oxygen containing three oxygen atoms.
• It is mainly found in the stratosphere, where it forms the ozone layer.
• The ozone layer protects Earth from harmful ultraviolet (UV) radiation.

Last verified on 30-06-2026

Explanation

• The Sun is the ultimate and main source of energy on Earth.
• It provides energy through solar radiation (light and heat).
• All forms of energy on Earth directly or indirectly come from the Sun.
• It supports life, climate, and ecosystems on Earth.

This energy is then converted into various forms, such as:

• Thermal energy (heat)
• Kinetic energy (wind, water currents)
• Electrical energy (generated from solar panels)
• Chemical energy (fossil fuels, biomass)
• Biological energy (food chains, ecosystems)

Last verified on 16-06-2026

Explanation

• A rectifier is an electrical device that converts Alternating Current (AC) into Direct Current (DC).
• It allows current to flow in only one direction.
• It is commonly used in power supplies and chargers.
• Rectifiers use components like diodes for conversion.

Last verified on 25-06-2026

Explanation

• Neptune is the farthest planet.
• It was visited by the spacecraft Voyager 2.
• It's is a very windy place.
• It has six rings.
• It has 14 moons.

Last verified on 24-06-2026