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52 Cards in this Set
- Front
- Back
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Electrodynamics |
The study of moving electrical charges |
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What causes electric current? |
The flow of charged particles (electrons) |
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3 conditions that will allow a current to flow |
1. In a vacuum 2. In a gas 3. In a metallic conductor |
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For the electrons to flow, there needs to be ____ of electrons at one end of the conductor and a ___ of electrons at the other. |
An excess; deficiency |
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Electrons move from the ___ # to the __ # |
High; low |
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Circuit- |
The path over which the current flows |
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A ___ is needed to create an electrical current. |
Source 1. Battery (DC) 2. Generator |
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2 sources of electrons |
Battery (DC) Generator (AC) |
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3 factors that characterize a simple circuit. |
1. Potential difference 2. Current 3. Resistance |
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Potential difference |
The difference in electrical potential energy between 2 points in a circuit. |
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What gives the electrons the pull (force) to move through the conductor |
Potential difference |
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What is another term for potential difference? |
Electromotive force |
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What is the unit for potential difference? |
Volt |
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1 volt= |
1 joule of work done on 1 coulomb of charge |
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1 volt is the ___ ___that will maintain a ___ of 1 __ in a circuit whose ___is _ ohm. |
Potential difference; current; ampere; resistance; 1 |
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Current- |
The amount of electrical charges flowing per second |
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Units for current |
Ampere or milliampere |
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_ ampere = _ coulomb of charge flowing per second |
1;1 |
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1 amp= _ coulomb/ sec |
1 |
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1 coulomb = ___ electrons |
6.3 × 10^18 |
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1 amp= _ e-/sec |
6.3x10^18 e-/sec |
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Resistance- |
anything that opposes or hinders the flow of electrical current |
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Unit for resistance |
Ohm |
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Resistance is ____ (within the conductor) and ___ (load) |
Inherent; added |
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inherent resistance in a wire is dependent upon: |
1)conducting material 2) length of the wire 3)cross sectional area 4) temperature |
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resistance: conductors insulators semi conductors superconductors |
low resistance high resistance intermediate no resistance |
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the longer the wire, the more or less resistance? |
more resistance |
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the greater the cross sectional area, the more/less resistance? |
less resistance |
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the greater the temperature if the wire, the more or less the resistance? |
more resistance |
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what is the formula for calculating resistance? |
R= p L/A |
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R= |
resistance |
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p(rho)= |
resistivity coefficient |
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L= |
length |
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A= |
cross-sectional area |
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the ohm's law is used for what? |
the mathematical relationship between current, potential difference, and resistance in a circuit |
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what is the formula for finding electrical current? |
I= V/R |
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I= |
electrical current in amperes (A) |
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V= |
potential difference in volts (V) |
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R= |
resistance in ohms (omega) |
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what is the current in a circuit that has a potential difference of 110 volts and a resistance of 20 ohms? |
5.5 A |
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How much potential difference does a circuit have that uses 15 amps of current and has a resistance of 40 ohms? |
600 V |
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V= |
I*R |
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R= |
V/I |
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An xray circuit uses a potential difference of 60 kV and 100 mA. What is the resistance in the circuit? |
600,000 ohms |
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what is the unit of power? |
watt |
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define watt |
one ampere of current flowing through one volt per second |
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what is the formula for calculating power? |
P= IV |
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How much power is produced in a circuit that has a potential difference of 220 volts and a current of 12 amps? |
2640 watts |
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what is the potential difference necessary for a 40 amp circuit to produce 1.4 megawatts of power? |
jj |
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in a circuit. some power is lost due to |
heat production |
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what is the formula used to calculate the loss of power? |
P= I^2R |
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How much heat is lost in a circuit that uses 24 amps of current and has a resistance of 15 ohms? |
aa |
