PHYSICS

• The ability of a certain naturally occurring rock to attract iron has been known since at least 600 b.c.
• The early Greeks called the rock that attracts iron Magnesian stone, as it came from the northern Greek county of Magnesia.
• The rock that attracts iron is known to be the black iron oxide mineral named magnetite.
• Substances that are attracted to magnets are said to have ferromagnetic properties, or simply magnetic properties.
• The north pole of a suspended or floating bar magnet currently points directly toward Earth's south magnetic pole.
• Earth's magnetic field is believed to originate deep within the earth.
• Like all other magnetic fields, Earth's magnetic field is believed to originate with moving charges.
• A device that measures currents from the strength of their magnetic fields is called a galvanometer.
• The armature, when connected to a power source, generates a magnetic field.
• The field magnet provides a constant external magnetic field.
• The brushes maintain electrical contact between the power source and the rotating armature.
• The commutator ensures a continuous unidirectional torque on the armature by reversing the current direction as needed.
• Electric motor is an electromagnetic device that converts electrical energy to mechanical energy.
• The discovery of electromagnetic induction was made independently in 1831 by Joseph Henry in the United States and by Michael Faraday in England.
• Electromagnetic induction involves the generation of a voltage, called an induced voltage, in a wire when the wire is moved in a magnetic field or when the magnetic field is changed.
• The resulting current in the wire from electromagnetic induction is also called an induced current.
• Electromagnetic induction is the process of generating electricity by moving magnets or changing magnetic fields near a wire.
• AC is the Standard for power distribution grids.
• AC is Efficient for long-distance power transmission.
• AC is Easily transformed to different voltage levels using transformers.
• AC is Commonly used in homes, businesses, and industrial applications.
• AC would flow back and forth.
• DC would flow in one direction.
• DC Commonly used in batteries for portable devices.
• DC Suitable for electronic devices and circuits that operate steady voltage.
• DC Used in many Tow-voltage applications, such as electronics telecommunications.
• DC Efficient for short distance power transmission.
• DC is The power supply for electronic gadgets the smartphones, laptops, and cameras.
• AC is the Standard for power distribution grids.
• AC is Efficient for long-distance power transmission.
• AC is Easily transformed to different voltage levels using transformers.
• AC is Commonly used in homes, businesses, and industrial applications.
• AC would flow back and forth.
• DC would flow in one direction.
• DC Commonly used in batteries for portable devices.
• DC Suitable for electronic devices and circuits that operate steady voltage.
• DC Used in many Tow-voltage applications, such as electronics telecommunications.
• DC Efficient for short distance power transmission.
• DC is The power supply for electronic gadgets the smartphones, laptops, and cameras.
• The transfer of heat that takes place by the movement of groups of molecules with higher kinetic energy is convection.