Parallel Circuit
(n.) Electrical circuit containing multiple loops (at least two), each containing only one component. In a parallel circuit, if one component fails, all the others continue to function normally.
Pascal, Blaise (1623-1662)
French philosopher, mathematician, and physicist. Showing an early interest in mathematics, Blaise Pascal invented a calculating machine around 1642. His famous Puy de Dôme experiment advanced his study on the weight of air and vacuum. He argued in favor of the existence of a vacuum in the part of the tube freed by the descent of mercury. The question of the vacuum was hotly debated at that time. He wrote a Treatise on the Void which was never published, followed by two memoirs on the equilibrium of liquids and the weight of air (published in 1663).
Pascal
(n.m.) Legal unit of pressure (Symbol Pa).
Period
(n.f.) Duration of the elementary pattern. It is denoted by T.
pH
(n.m.) Measure that characterizes the acidity and basicity of a solution. The pH at 25°C ranges between 0 and 14. An aqueous solution is acidic if its pH is less than 7, neutral if it is equal to 7, and basic if it is greater than 7.
Photocell
(n.f.) Generator that converts light energy into electrical energy.
Physical Quantity
(n.f.) A concept that can be measured and is associated with a unit.
Planet
(n.f.) Celestial body orbiting the Sun. It diffuses the Sun's light in all directions of space. The eight planets of the solar system, starting from the Sun, are: Mercury, Venus (known as the "Shepherd Star"), Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
Plastic Material
(n.) Material consisting of artificial macromolecules primarily containing carbon and hydrogen atoms.
Plumb Line
(n.) An instrument consisting of a heavy object suspended from a string. The plumb line is used to indicate the vertical.
Point Light Source
(n.) A light source of very small dimensions.
Polluted Air
(n.) Air that contains harmful substances (gases or smoke).
Potential Energy
(n.) Energy of height. The capacity of an object at a height to produce effects. The higher the object, the greater the effects produced. Potential energy depends on the intensity of gravity (g), mass (m), and height (h).
Ep = m × g × h where Ep is in joules, m is in kilograms, g (gravitational intensity) is in N/kg or m/s2, and h (height) is in meters.
Power Plant
(n.) Factory that produces electrical energy.
Power
(n.f.) Physical quantity equal to the energy consumed in one second. The unit of power is the watt (Symbol W). The power (in W) received by the receiver that transforms electrical energy into thermal or light energy is equal to the product of the effective voltage (in V) and the effective intensity (in A) for a variable voltage or the product of the voltage (V) and the intensity (A) for a continuous voltage.
Precipitate
(n.m.) Solid particles suspended in a liquid.
Pressure Sensor
(n.) Device used to measure pressure.
Pressure
(n.f.) Quantity measured with a barometer. A manometer or pressure sensor is also used. Its unit is the pascal (Pa).
Primary Light Source
(n.) An object that produces and emits light. It is said to emit light.
Product
(n.m.) Substance formed during a chemical transformation.
Proportionality
(n.f.) State of two quantities whose value ratio is a constant. The graph of the variations of one of these quantities as a function of the other is a straight line passing through the origin. In a proportionality table with two rows, all the numbers in one row are obtained by multiplying those in the other row by the same number: the proportionality coefficient.
Protocol
(n.m.) Set of instructions to be followed to successfully carry out a procedure, such as a chemical synthesis.
Pure Substance
(n.) Substance that contains only one chemical species. A pure substance is often characterized by changes of state that occur at constant temperature.
Examples:
The solidification or melting of pure water occurs at 0°C.
The liquefaction or boiling of pure water under normal pressure (1,013 hPa) occurs at 100°C.