If a body is more dense than water, it will be heavier than an equal volume of water. This means the downward force of gravity will exceed the upward buoyant force that acts on it. Net force will be downward, hence it sinks. Electrical resistance is the opposition a conductor offers to the migration of electrons. It depends on what material the wire is made of as well as the dimensions of the wire.
Resistance generally increases with increasing temperature.
In some materials, called superconductors, resistance decreases to zero at critically low temperature. Sunshine is light, which is part of the electromagnetic spectrum, all of which is produced by accelerating electric charges. All light is electromagnetic waves, the result of electromagnetic induction. An echo is simply reflected sound. Because sound from a small source spreads out via the inverse square law, sound intensity per unit area decreases with distance to the reflecting surface, and when reflected continues to decrease with distance.