Physics

Mechanical waves require a material medium (solid, liquid, or gas) to propagate, unlike electromagnetic waves which can travel through a vacuum. Therefore, the correct answer is mechanical waves.

A fuse is designed to protect electrical circuits by breaking the circuit when the current exceeds a safe level, thus preventing damage from high current. It does not directly protect against high voltage or overheating, although it indirectly prevents overheating by stopping excessive current.

In metallic conductors, electric current is primarily due to the flow of free electrons, which are negatively charged particles that move through the metal lattice when a potential difference is applied. Protons and neutrons do not move freely in a conductor, and the mechanism is well established, so it is not under controversy.

The frequency of a simple pendulum is independent of the mass of the bob. It depends only on the length of the pendulum and gravity. Therefore, replacing the bob with a heavier one does not change the frequency; it remains f.

At absolute zero (0 K), the thermal vibrations of atoms in a conductor cease, causing the resistance to drop to nearly zero. This is because resistance in conductors primarily arises from lattice vibrations, which are absent at absolute zero.

A potential divider circuit provides a continuously varying output voltage (potential) by dividing the input voltage in proportion to the resistances. This is why it is called a potential divider.

Newton's laws of motion are classical mechanics laws that accurately describe the motion of particles at everyday speeds. However, they fail for particles moving at velocities close to the speed of light, where relativistic effects become significant and special relativity must be used instead.

The blue color of the sky is caused by Rayleigh scattering, where shorter blue wavelengths of sunlight are scattered more than other colors by the molecules in the atmosphere.

Sound requires a medium (solid, liquid, or gas) to propagate as it travels by vibrating particles. In a vacuum, there are no particles to transmit sound waves, so the velocity of sound is zero.

Internal resistance is the resistance offered by the source of EMF (such as a battery or cell) to the flow of current within itself. It is an inherent property of the source, not of external components like conductors, resistors, or capacitors.