Explanation

The resistance of a wire is directly proportional to its length (R ∝ L).

If the length is doubled and the area remains the same, the resistance will also double.

Explanation

Deca (symbol: da) is the SI prefix that represents a factor of 10.

It is used to denote ten times the base unit, such as 1 decameter = 10 meters.

Explanation

The distance between the optical center and the principal focus is called the focal length of the lens.

while

A negative focal length indicates that the system diverges light.

Explanation

Paksat-IR was launched on August 11, 2011, as Pakistan’s first geostationary communication satellite.

It was developed with the help of China.

It provides telecommunication and broadcasting services.

Explanation

• The Soviet Union launched the first artificial satellite in space.
• It named Sputnik 1, on October 4, 1957.

Explanation

Ernest Rutherford, a British physicist probed atoms with alpha particles.

He was known as the “father of nuclear physics”.

He was awarded the Nobel prize for his contribution to the structure of the atom in 1908.

Explanation

The force the earth attracts a body towards itself is called weight.

It is not constant but varies from place to place due to changes in the value of g

 Since it is a force, its SI unit is also Newton (N).

Explanation

Objects that orbit around a planet are called satellites.

These can be natural, like the Moon, or artificial, like communication satellites.

Explanation

The to and fro movement of a pendulum is called a vibration or oscillation.

It's a repeated back-and-forth motion about a central position.

Explanation

When a sound wave strikes a surface and bounces back into the original medium, this is called reflection.

It’s the same principle behind echoes.