Explanation

Signal jammers block or interfere with radio frequencies to stop communication.

They are used for security or preventing unauthorized transmissions.

Explanation

Radiation: Gas heaters emit infrared radiation that heats up objects and people directly.

Convection: The heated air rises and circulates around the room, warming it through convection.

Explanation

According to Coulomb's Law, the force between two charges decreases as the square of the distance between them increases.

Formula: F ∝ 1/r², where r is the distance between the charges.

Explanation

An object floats if its density is less than the liquid's density.

An object sinks if its density is greater than the liquid's density.

Explanation

Upthrust (or buoyant force) happens only when a body is physically in contact with a liquid.

Electrostatic magnetic force between two magnets, and gravitational forces act at a distance without contact.

Explanation

A magnetic compass needle aligns itself with the Earth’s magnetic field.

Therefore, it always points in the North-South direction.

Explanation

The solar energy that reaches the Earth annually is far more than the world's total energy consumption, with estimates suggesting it is more than 10,000 times the current global energy needs.

This vast amount of energy highlights the potential of solar power as a renewable energy source.

Explanation

Medicine in a teaspoon is measured in milliliters (mL) as it is a small liquid quantity.

A standard teaspoon holds approximately 5 mL of liquid.

Explanation

Wave velocity is the distance a wave travels per second in a given medium.

It is calculated as Velocity (v) = Frequency (f) × Wavelength (λ).

Explanation

The reason is that the rails expand in summer

. The gap is provided to allow for this expansion.

If no gap is left the expansion in summer will cause the rails to bend sideways

This may result in train accidents.