Specific Resistance (”ρ”) is a property of any conductive material, a figure used to determine the end-to-end resistance of a conductor given length and area in this formula:
R = ρl/
A. Specific resistance for materials are given in units of Ω-cmil/ft or Ω-meters (metric).
What is the formula resistance?
Resistance has units of ohms (Ω), related to volts and amperes by
1 Ω = 1 V/A
. There is a voltage or IR drop across a resistor, caused by the current flowing through it, given by V = IR.
How do you calculate the resistance of a wire?
Use the results to calculate the resistance of each length of wire by using
R = V/I
, where R is resistance, V is voltage and I is current.
What is the resistance of a wire?
The ohm is the common unit of electrical resistance, equivalent to one volt per ampere and represented by the capital Greek letter omega, Ω. The resistance of a
wire is directly proportional to its length and inversely proportional to its cross-sectional area
.
Does the length of wire affect resistance?
The resistance of a long wire is greater than the resistance of a short wire because electrons collide with more ions as they pass through. The
relationship between resistance and wire length is proportional
.
How does the resistance of wire depend on its length?
Resistance is directly proportional to the length of the conductor. So, as the length increases, the magnitude of resistance increases. … Resistance is
inversely proportional to the cross-sectional area of the conductor
. Thus, the resistance of the conductor decreased with the decrease in cross-sectional area.
How do you solve for resistance?
- To find the Voltage, ( V ) [ V = I x R ] V (volts) = I (amps) x R (Ω)
- To find the Current, ( I ) [ I = V ÷ R ] I (amps) = V (volts) ÷ R (Ω)
- To find the Resistance, ( R ) [ R = V ÷ I ] R (Ω) = V (volts) ÷ I (amps)
- To find the Power (P) [ P = V x I ] P (watts) = V (volts) x I (amps)
What is the rule for resistance in a series circuit?
The total resistance of a number of resistors in
series is equal to the sum of all the individual resistances
.
How do you find the resistance of a series?
- RT = R1 + R2 + R3.
- 2 + 2 + 3 = 7 Ohms.
- R total is 7 Ohms.
What is the resistance of steel wire?
| Material Resistivity (ohm-cmil/ft) Resistivity (10 − 6 ohm-cm) | Nickel 41.69 6.93 | Platinum 63.16 10.5 | Stainless steel (304) 541 90 | Steel (0.5% carbon) 100 16.62 |
|---|
What are the four things that affect the resistance of a wire?
- The type of material of which the resistor is made.
- The length of the resistor.
- The thickness of the resistor.
- The temperature of the conductor.
What is the resistance of a Nichrome wire?
| Material Resistivity (OHM-CMIL/FT) Resistivity (10−6 OHM-CM) | Nichrome 675 112.2 | Nichrome V 650 108.1 | Nickel 41.69 6.93 | Platinum 63.16 10.5 |
|---|
Which change decreases the resistance of a piece of copper wire?
Resistance decreases as copper (or any other metal)
is cooled
. Its atoms vibrate less, and so they impede the flow of electrons less. Pure copper has less resistance than copper containing impurities. Impurity atoms are a different size to copper atoms, so they get in the way of moving electrons.
How do you reduce resistance in a wire?
Changing the material, increasing the cross section area, lowering the temperature
, and using a thicker wire are some of the ways to reduce resistance.
Does temperature affect resistance of a wire?
Heating a metal conductor makes it more difficult for electricity to flow through it. … Heating the metal conductor causes atoms to vibrate more, which in turn makes it more difficult for the electrons to flow,
increasing resistance
.
Why the resistance is directly proportional to length?
As the
length increases
, the number of collisions by the moving free electrons with the fixed positive ions increases as more number of fixed positive ions are present in an increased length of the conductor. As a result, resistance increases.
