An equation for electrical power is P=IV where P is the power, I is the current

Question

An equation for electrical power is P=IV where P is the power, I is the current and V is the voltage.

a.) Using Ohm's law, V=IR, write the equation for power in two different ways, one without current and one without voltage.

b.) One of these equations implies that power is proportional to R and one implies that power is proportional to 1/R. How do you resolve this apparent discrepancy?

c.) Suppose a resistor is attached to a battery with no other components. We want to know how the power changes if the resistance changes.

d.) By what factor does the power change when the resistance is doubled? What about the current?

e.) What should happen with the power if the resistance is heated up: would the power increase or decrease? Explain.

Explanation / Answer

electric power P = V*I
a)

   P= V*I

from Ohm's law V = IR

substitute V = I*R in P= V*I

   P = I*R*I

   P = I^2*R

and I = V/R

   P = V*V/R

   P = V^2/R

c) P = V*I, power delevered by the source of emg ,to the componets in the circuit .

   and P = I^2*R is power dissipated at the resistor

if only resistor is connected in the circuit then the power will be dissipated at the resistor, as the resistor changes the power dissipatation at the resistor is also increases

d) if resistor increased that is doubled then the power dissipated also increased by two times

e)for a conductor if temperature increased by heating then the resistance increases so the power dissiopation also

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