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We know that power is current squared times resistance, and also voltage squared divided by resistance.

P=(I^2)*R

i.e. P is directly proportional to R..................(1)

P=(V^2)/R

i.e. P is inversely proportional to R................(2)

This presents a contradiction. Why does this contradiction occur and which among (1) and (2) is correct?

I've been wondering about this for long and am confused. Help will be greatly appreciated! Thank you.

10 years ago

It depends on resistance.

So u cannot take I as independent quantity

Since on changing the resistance both i and P will change.

To find relationship u need to have constant before proportionality

like:

P is proportional to (contant* R)

So we have to take

P = V^2/R

Since V is constant in the circuit

and thus we can say

P is inversely proprtional to R^2

Plzzzzz approve my answer by clicking on yes below!

10 years ago

10 years ago

P=(I^2)*R

IF CURRRENT IS CONSTANT THEN POWER IS DIRECTLY PROPORTIONAL TO RESISTANCE

AS HAPPENS IN SERIES CONNECTION.SUPPOSE THREE RESISTANCE 2,3&5OHM ARE CONNECTED IN SERIES THEN POWER CONSUMPTION

ORDER IS 5ohm>3ohm>2ohm.THIS IS BECAUSE DUE TO CONSTANT CURRENT IN THREE RESISTANCES" POWER CONSUMED~RESSTANE"

#P=V^2/R

IF POTENTIAL DIFF. IS CONSTANT THEN POWER IS INVERSELY PROPORTIONAL TO RESISTANCE

AS HAPPENS IN PARALLEL COMBINATION OF RESISTANCES. LET THREE RESISTOR OF INDIV. RESISTANCES 2,3&5 ohm CONNECTED IN PARALLEL THEN THE ORDER OF POWER CONSUMPTION IS AS FOLLOW

2ohm>3ohm>5ohm

the above trend is because power varies inversly with resistance in parallel combination

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7 years ago

6 years ago

Hello friend i am hemant

The formula P = V^2 / R says that "If you keep the volts constant ( and permit the current to alter as it will ) then the power is inversely proportional to the resistance."

The formula P = I^2 R says that "If you keep the current constant ( and in turn permit the volts to vary accordingly) then the power consumed is proportional to the resistance".

The formula P = I^2 R says that "If you keep the current constant ( and in turn permit the volts to vary accordingly) then the power consumed is proportional to the resistance".

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