Explanation

• Global Positioning System (GPS) is a satellite-based navigation system used to monitor the location and movement of vehicles, ships, and aircraft.
• Developed by the United States, it provides accurate position, navigation, and timing information worldwide.
• Widely used in transportation, mapping, military operations, and smartphones.

Last verified on 12-03-2026

Explanation

• A stopwatch that measures to 0.1 seconds is typically a mechanical (analog) stopwatch
• The 0.1-second value represents the "least count" of the mechanical instrument
• Digital stopwatches often measure to 0.01s.
• These are commonly used in laboratories for timing experiments. 

Last updated 11-02-2026

Explanation

Explanation

The least count of a screw gauge in millimeters is:

$$\text{LC}=0.01\text{ mm}$$

To convert millimeters to centimeters:

$$1\text{ mm}=0.1\text{ cm}$$$$0.01\text{ mm}=0.01\times 0.1=0.001\text{ cm}$$

Explanation

The least count of a screw gauge is the smallest measurement it can measure.

Formula:

$$\text{Least Count }=$$Pitch/Number of divisions on circular scale ​

In a typical screw gauge:

• Pitch = 0.5 mm

• Circular scale divisions = 50

Least Count=0.5/ 50 ​=0.01 mm

$$Last\; updated\; 11-02-2026$$

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

• Solar panels convert sunlight into electrical energy using special cells.
• Solar energy is a renewable and clean source of energy.
• These cells are called photovoltaic (PV) cells because they generate electricity when exposed to light.
• The technology is based on the photovoltaic effect, discovered in 1839.

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

• When water cools from 4°C to 0°C, it expands as it freezes into ice.
• Unlike most substances, water’s maximum density is at 4°C; below this temperature, the volume increases and density decreases.
• This is why ice floats on water.

Last verified on 10-03-2026

Explanation

• Combustion is a chemical reaction in which a substance reacts rapidly with oxygen to produce heat and light.
• Commonly observed when wood, coal, or fuel burns.
• Combustion is an exothermic reaction because it releases energy.

Last verified on 10-03-2026