Can you kill yourself with a 9 volt battery?. Resistivity Current Density of a conductors depends on...
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Transcript of Can you kill yourself with a 9 volt battery?. Resistivity Current Density of a conductors depends on...
• Can you kill yourself with a 9 volt battery?
Resistivity
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J =E
ρ
ρ =E
J
ρ =V m
A m2 =V ⋅mA
=V
A⋅m =Ω⋅m
•Current Density of a conductors depends on Electric Field and the properties of the material
•Those properties are symbolized with the Greek letter rho and referred to as resistivity
•The unit for resistivity is Ohm-meters
•Resistivity changes with temperature
Zero-Resistivity Superconductors
Superconductors are used to make medical scanners, magnetometers, and rail guns
Resistivity & Resistance
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R =ρL
A•Unit for Resistance is Ohms (Ω)
•Resistance is higher for wires of longer length
•Resistance decreases with larger cross-sectional areas
Conductance
• The reciprocal of Resistance
• Lord Kelvin called the unit the mho
• Officially the Siemens
• 1 mho = 1 Siemens
Ohm’s Law
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E = ρJ
V
L=I
Aρ
V = IρL
AV = IR
Units
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V = IR
Volts = Amps⋅Ohms
Ohms =Volts
Amps
I-V Graph for Ohmic Material
Diode: Ohmic or Not Ohmic?
Guess the Resistors!