- Joined
- Mar 6, 2010
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This is bothering me, they say light bulb filaments and toasters use high resistance wires since they want to convert electric energy to heat energy.
But then I look at the formulas.
V = IR
P = IV
Wall outlets have 120V, lower Resistance means higher current. Current goes into the power formula.
So [Low Resistance] -> Really high current - > Powerful toaster 😕
Shown in numbers, power used by a 1ohm resistor vs a 120 ohm resistor
**1 ohm filament in a toaster**
V=IR
120V = 1ohm * 120 amps
P= V*I
P= 120amp * 120 Volts
Power used by 1 ohm resistor = 14,400 Watts
**120 ohm filament in a toaster**
V=IR
120V = 120ohm * 1 amp
P= V*I
P= 1amp * 120 Volts
Power used by 1 ohm resistor = 120 Watts
The numbers say a weak resistance in the toaster (or lightbulb) makes for a large power output. But intuition tells us we want our toasters and lightbulb filaments to be high resistance wires... right?😕
But then I look at the formulas.
V = IR
P = IV
Wall outlets have 120V, lower Resistance means higher current. Current goes into the power formula.
So [Low Resistance] -> Really high current - > Powerful toaster 😕
Shown in numbers, power used by a 1ohm resistor vs a 120 ohm resistor
**1 ohm filament in a toaster**
V=IR
120V = 1ohm * 120 amps
P= V*I
P= 120amp * 120 Volts
Power used by 1 ohm resistor = 14,400 Watts
**120 ohm filament in a toaster**
V=IR
120V = 120ohm * 1 amp
P= V*I
P= 1amp * 120 Volts
Power used by 1 ohm resistor = 120 Watts
The numbers say a weak resistance in the toaster (or lightbulb) makes for a large power output. But intuition tells us we want our toasters and lightbulb filaments to be high resistance wires... right?😕