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The resistance of a conductor is determined by the length, cross-sectional area, and resistivityof the conductor. Since temperature affects resistivity, resistance is indirectly affected by temperature.
Resistance is directly-proportional to the length of the conductor and inversely-proportional to its cross-sectional area, and resistivity is its constant of proportionality. If the length of the conductor is expressed in metres, and the cross-sectional area is expressed in square metres, then resistivity is expressed in ohm metres. Using American units of measurements, however, where length is expressed in feet and cross-sectional area in circular mils, resistivity is normally expressed in 'ohm circular mill per foot' (not, as often seen in textbooks: 'ohms per circular mil foot'!).
In the case of d.c. current, the charge carriers distribute themselves across the entire cross-sectional area of the conductor. In the case of a.c. current, however, due to what is known as the 'skin effect', there is a tendency for the charge carriers to move closer to the surface of the conductor -this acts to reduce the effective cross-sectional area of the conductor and, thus, raise its resistance. So a conductor's resistance to a.c. is somewhat higher than it is to d.c., and is generally termed its 'a.c. resistance'. A.C. resistance increases with frequency (and should not be confused with 'reactance' or 'impedance').
What else can I help you with?
What are the differences in voltage drop between AC and DC systems?
In AC systems, voltage drop is affected by factors like resistance and reactance, leading to a more complex calculation. In DC systems, voltage drop is mainly influenced by resistance, resulting in a more straightforward calculation.
What are some things related to electricity?
Circuits, conductors, insulators, voltage, resistance, current, AC/DC, power generation, outlets, transformers, electric shocks.
What device has the smallest current in parallel circuit?
In a parallel circuit, each branch has its own current flow, so there isn't a single device that has the smallest current. The current through each device is determined by its resistance and voltage applied. The device with the highest resistance will have the smallest current flowing through it in a parallel circuit.
Why current is supplied to DC motor?
What supplies a dc motor is not current, but voltage. Current is what flows in the circuit formed by the dc motor and for the charge. That current varies according to the resistance of the circuit.
What is the relationship between current resistance and potential difference?
The first, and perhaps most important, relationship between current, voltage, and resistance is called Ohm's Law, discovered by Georg Simon Ohm and published in his 1827 paper, The Galvanic Circuit Investigated Mathematically. Ohm's principal discovery was that the amount of electric current through a metal conductor in a circuit is directly proportional to the voltage impressed across it, for any given temperature. Ohm expressed his discovery in the form of a simple equation, describing how voltage, current, and resistance interrelate:E = IRIn this algebraic expression, voltage (E) is equal to current (I) multiplied by resistance (R). Using algebra techniques, we can manipulate this equation into two variations, solving for I and for R, respectively: I = E/R and R = E/I.answer discovered that relation only after VOLTA establish the voltage relationship and AMPERE discovered the current relationship. and of course WATTS establish the power.521R=VResistanceOHMSoli
What resistance is needed to reduce 5V dc to 4V dc?
The resistance needed is1/(the current flowing through the resistance) ohms.
What resistance is needed to reduce 5V DC to 3V DC?
12v dc to 3v dc
What is a difference between DC and ac resistance and expline DC resistasce?
DC is just direct current into a resistance it is a linear function. AC if the resistance is non reactive it would be the same linear function.
Why dc shunt generator does not have armature resistance?
It does have armature resistance.
What resistance is needed to reduce 12V dc to 5V dc?
7K ohm
Dc resistance of diode is a static resistance b dynamic resistance c high resistance d zero resistance?
B - Dynamic resistance
What is ac and DC resistance of a diode?
diodes follow an exponential curve meaning non linear in nature. by using Boltzmann formula an impedance can be calculated. That would be the AC Resistance the dc resistance on any device is the voltage drop divided by the dc current.
Why armature resistance is less than 1 Ohm?
why armature resistance is very low as compare to field resistance in dc motor
How to calculate the resistance to step down DC voltage?
Connect a variable resistance across DC source (fixed ends of variable resistor or Rheostat) and take decreased DC output across its one fixed terminal and other variable terminal of variable resistor. Other method is connect variable resistor in series with DC output and load, vary the resistance and take decreased DC voltage as required.
Why dc supply is being used in studying the effect of temperature on the field winding resistance of a dc motor?
Because tests on a dc motor are always done using dc.
A 100KVA DC GENERATOR HAS ARMATURE RESISTANCE 0.02 OHMS AND A SERIES FIELD RESISTANCE 0.004 OHMS WHAT IS THE ARMATURE GENETATED VOLTAGE?
There is not enough information to answer the question. A DC generator is never described in kVA because DC generators are specified in terms of kilowatts.
How many things can a multi meter measure?
Resistance Voltage (both AC and DC) Current (both AC and DC)
