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the magnetic field B changes (e.g. an alternating magnetic field, or moving a wire loop towards a bar magnet where the B field is stronger), the wire loop is deformed and the surface Σ changes, the orientation of the surface dA changes (e.g. spinning a wire loop into a fixed magnetic field), any combination of the above
A few two-signal-wire systems lingered on; the Cooke and Wheatstone two-needle system used on British railways, [10] and the Foy-Breguet telegraph used in France. [11] With the reduction in the number of signal wires, the cost of the return wire was much more significant, leading to earth return becoming the standard. [12]
The ground potential at different outlets may differ by as much as 10 to 20 volts [4] due to voltage drops from these currents. The diagram shows leakage current from an appliance such as an electric motor A flowing through the building's ground system G to the neutral wire at the utility ground bonding point at the service panel.
A time-domain reflectometer; an instrument used to locate the position of faults on lines from the time taken for a reflected wave to return from the discontinuity.. A signal travelling along an electrical transmission line will be partly, or wholly, reflected back in the opposite direction when the travelling signal encounters a discontinuity in the characteristic impedance of the line, or if ...
The line to neutral voltage is half the line-to-line voltage. Lighting and small appliances may be connected between a line wire and the neutral. Higher-power appliances, such as cooking equipment, space heating, water heaters, clothes dryers, air conditioners and electric vehicle charging equipment, are connected to the two line conductors.
But when the inducing charge is moved away, the charge is released and spreads throughout the electroscope terminal to the leaves, so the gold leaves move apart again. The sign of the charge left on the electroscope after grounding is always opposite in sign to the external inducing charge. [5] The two rules of induction are: [5] [6]
The "protective earth" (PE) safety ground wires in AC utility building wiring were not designed for, and cannot be used as an adequate substitute for an RF ground. The long utility ground wires have high impedance at certain frequencies. In the case of a transmitter, the RF current flowing through the ground wires can radiate radio frequency ...
Air moving past an aircraft can lead to a buildup of charge called "precipitation static" or "P-static"; aircraft typically have one or more static wicks to remove it. [143] Checking the status of these is a standard task for pilots. [144] Similarly, helicopter blades move fast, and tribocharging can generate voltages up to 200 kV. [145]