Science Physics Title 'S'

Superconductors are substances with resistance to current that falls effectively to zero a few degrees above absolute zero. Magnets powered by coils of superconducting materials are in widespread use already. Transmission of electric power by superconducting cable will await the development of materials that are modestly priced, available in bulk and retain their superconducting properties at temperatures higher than the boiling point of liquid air.

Superposition is the process by which two waves combine into wavefrom when they overlap.

Surface tension is the force of contraction within the surface of a liquid brought about by the imbalance of intermolecular forces on the surface molecules. The forces act in all directions parallel to the liquid surface.  The action of surface tension is particularly clear in the small, spherical drops of water that form on a greasy surface and in the perfect roundness of soap bubbles.
An important consequence of surface tension is the drop in pressure across concave surface into a liquid mass (meniscus). This drop in pressure is essential to the penetration of the soil by water (capillary action) and to the water pressure balance within plants, which is essential to transpiration. The modest increase in pressure when penetrating a convex surface accounts for the slightly higher pressure in bubbles, for the spherical shapes o water droplets and for the maximum height above a greasy surface to which a water droplet can grow. The rise of a liquid in a clean, uniform glass tube offers a method of measuring surface tension.

Systematic error: An inherent error in an instrument or in technique that cannot be reduced or eliminated by averaging the results of several measurements. Systematic error is guarded against by analysis and care. Examples include zero error, measuring the wrong distance for a pendulum length or a falling body, poor  instrument calibration and falling to correct for background radiation.