# physics helpWatch

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#1
can someone please explain this to me as it literally makes no sense to me in my head
ive watched freesciencelessons but i still don't get it
the total resistance of the two resistors in parallel is less than the resistance of the smallest resistor
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3 weeks ago
#2
Just use the formula 1/R = 1/R + 1/R
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3 weeks ago
#3
(Original post by frenchfrench)
can someone please explain this to me as it literally makes no sense to me in my head
ive watched freesciencelessons but i still don't get it
the total resistance of the two resistors in parallel is less than the resistance of the smallest resistor
Think of electricity as water. The voltage across the resistors is the pressure driving the current / flow. It doesn't change whether you have one or many resistors in parallel. The pressure will cause the same current to flow through every resistor. If you have two in parallel, you will have twice the flow / current as having one, so have halved the effective resistance.
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3 weeks ago
#4
I was STUCK ON THE EXACT SAME THING
1
3 weeks ago
#5
(Original post by frenchfrench)
can someone please explain this to me as it literally makes no sense to me in my head
ive watched freesciencelessons but i still don't get it
the total resistance of the two resistors in parallel is less than the resistance of the smallest resistor
As rogeroxon said resistors in parallel have the same PD across them.

so if you have a low value resistor and a high value resistor in parallel with a voltage across them, the low value resistor will pass the current Ohm's law tells you to expect for that resistor... but the high value resistor parallel to it will always pass some extra current as well - so the parallel pair always passes more current than just the lower value resistor alone.

more current than the low value resistor alone at the same voltage means lower total resistance.

But just remember the 1/Rtotal=1/R1+1/R2... rule tbh.
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#6
do you need to know that formula for gcse?
(Original post by Joinedup)
As rogeroxon said resistors in parallel have the same PD across them.

so if you have a low value resistor and a high value resistor in parallel with a voltage across them, the low value resistor will pass the current Ohm's law tells you to expect for that resistor... but the high value resistor parallel to it will always pass some extra current as well - so the parallel pair always passes more current than just the lower value resistor alone.

more current than the low value resistor alone at the same voltage means lower total resistance.

But just remember the 1/Rtotal=1/R1+1/R2... rule tbh.
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