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    Voltage, also referred to as electrical potential difference, or an electric tension, is the electric potential difference between two points, or the difference in electric potential energy of a unit test charge transported between two points. It is measured in units of electric potential, volts or joules per coulomb. Voltage is equal to the work done per unit charge against a static electric field to move the charge between two points.

    A voltage can represent either a source of energy, lost, used or stored energy. A voltmeter is used to measure the voltage between two points in a system. Voltage can be caused by static electric fields by electric current through a magnetic field, by time-varying magnetic fields, or some combination of these.

    Similar to mechanical potential energy, the zero of potential can be chosen at any point so the difference in voltage is the quantity which is meaningful. The difference in voltage measured when moving across point A to point B is equal to the work which would have to be done, per unit charge, against the electric field to move the charge from A to B. This voltage between the two ends of the path is the total energy required to move an electric charge along the path divided by the magnitude of the charge. This relationship can be mathematically modeled as the line integral of the electric field and the time rate of change of magnetic field along that path.

    Voltage is defined so that negatively charged objects are pulled towards higher voltages, while positively charged objects pull towards lower voltages. This follows the principle that opposites attract. The conventional current in a wire or resistor always flows from higher voltage to lower voltage. It is possible for current to flow from lower voltage to higher voltage, but only when a source of energy is present to push it against the opposing electric field. 

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    BrainMass Categories within Voltage

    Kirchhoff's Voltage Law

    Solutions: 36

    Kirchhoff's Voltage Law states that the total voltage around a closed loop system must be equal to zero.


    Solutions: 167

    EMF is the voltage generated by a battery.

    BrainMass Solutions Available for Instant Download

    Plot Graph Corresponds

    Figure 1.38 shows the intensity of X-rays produced from a source as a function of their energy. With respect to the reference graph shown on the left, one plot corresponds to a decrease in tube current and the other to a decrease in the accelerating voltage (kVp). Explain which plot corresponds to a decrease in which parameter.

    Electricity Problems

    A step-up transformer has 200 turns in the primary coil and 3000 in the secondary coil. The primary coil sees 90 V. What is the voltage out of the secondary? B. if the secondary current is 2.00 A, what is the primary current? C. What is the power in the primary coil?

    Calculating the Maximal Charge

    Consider a parallel-plate capacitor having a separation of d=0.1mm and a capacitance of Co=11nF when having a vacuum between its plates. If the region between the plates is now completely filled with 19g of silicone oil, determine the maximum amount of charge that can be placed on the plates before dielectric breakdown occurs.

    Problems Involving Propagation of Measurement Error

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    Voltage of Terminal Apparatus

    The overhead cable supplying an outbuilding from the 230V supply has a resistance of 0.9 ohms. A2kw radiator and a 1500w kettle both rated at 230v are in use at the same time. DETERMINE THE VOLTAGE AT THE TERMINALS OF THIS APPARATUS. What WOULD BE THE VOLTAGE IF A 750w; 240Vwater heater was also switched on?

    Calculating the Total Current

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    Solve for Node Voltage; Write KCL and KVL Equations

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    Electricity: Current, Voltage and Resistance

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    A problem determining capacitance & PD across spherical cap

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    Capacitance Problem

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    Electrons have been transferred when difference in the plates

    A capacitor has a capacitance of 2.32E-8 F. In the charging process, electrons are removed from one plate and placed on the other plate. When the potential difference between the plates is 460 V, how many electrons have been transferred? Please solve and explain problem.

    Energy in a Capacitor: Acetylene Gas

    Acetylene gas is leaking from a cylinder in the immediate vicinity of an insulated conveyor belt which has built up a charge of 2.0µC. If the conveyor belt has a capacitance of 80pF, is there a danger of the acetylene being ignited? Consider both energy and voltage in your answer.

    Magnetic Fields and Forces.

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    Electrostatics: Capacitance of a spherical capacitor.

    A spherical capacitor is formed from two concentric, spherical conducting shells separated by vacuum. The inner sphere has radius 15.0 cm, and the capacitance is 116 pF. 1.) What is the radius of the outer sphere? 2.) If the potential difference between the two spheres is 220 V, what is the magnitude of charge on each sph

    Electrostatics: Capacitance of a Cylindrical Capacitor

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    Algebra Based Physics

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    Deriving Telegraph Equations

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    The batteries in a portable CD player are recharged by a unit that plugs into a wall socket. Inside the unit is a step-down transformer with a turns ratio of 1:13. The wall socket provides 120 Volts. What voltage does the secondary coil of the transformer provide?

    Maximum Voltage Applied

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    Battery Problem

    A battery charger is connected to a dead battery and delivers a current of 6.0 A for 5 hours, keeping the voltage across the battery terminals at 12 V in the process. How much energy is delivered to the battery?

    Resistance in a Wheatstone bridge

    A simple Wheatstone bridge has arms of R1 = 120 ohm, R2 =100 ohm and R3 =125 ohm. What is the value of R4 for balance? If R4 = 200 ohm and the bridge is driven with a source of 200 V. What is the open circuit voltage?

    Input and Output Voltage

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    Sufficient Energy of Capacitor

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    Easy Capacitor Problem

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