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

• 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

• 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

• 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

• The SI unit of electrical resistance is Ohm (Ω).
• It measures how much a material opposes the flow of electric current.
• Higher resistance means less current flows.
• It is defined by V = IR (Ohm’s Law).
• 1 Ohm = 1 Volt per Ampere.

Last verified on 10-06-2026

Explanation

When white light passes through a prism, it splits into 7 colors, forming a spectrum known as a rainbow:

1. Red
2. Orange
3. Yellow
4. Green
5. Blue
6. Indigo
7. Violet

The separation of visible light into its different colours is known as dispersion.

Last verified on 08-06-2026

Explanation

• Pressure in gases is due to the collision of gas molecules with the walls of the container.
• Gas molecules are in constant random motion.
• They continuously strike the container walls.
• These collisions create force per unit area (pressure).
• More collisions mean higher pressure.

Last verified on 08-06-2026

Explanation

• Short-sightedness is called Myopia.
• It is corrected by a concave lens.
• This lens is thin in the center and thick at edges.
• It helps light focus on the retina correctly.
• Without correction, distant objects look blurred.

Additional information:

• Long-sightedness is called Hypermetropia.
• It is corrected by a convex lens.
• This lens is thick in the center and thin at edges.
• It helps light focus on the retina properly.
• Without correction, near objects look blurred.

Last verified on 07-06-2026

Explanation

• A barometer measures atmospheric (air) pressure.
• It helps in weather forecasting, detecting storms, and studying climate changes.
• Two common types of barometers: mercury barometer and aneroid barometer.

Last verified on 13-03-2026

Explanation

• Violet light has the smallest wavelength, approximately 380-450 nanometers (nm).
• While red light has the longest wavelength, approximately 620-750 nanometers (nm).
• The order of colors in the spectrum, from longest to shortest wavelength, is: Red, Orange, Yellow, Green, Blue, Indigo, Violet (ROYGBIV).

Last verified on 01-04-2026