Basic circuit - power supplied

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Homework Statement

In the Figure below if V 1=10 V and i x= -2 A, what is the power supplied by the dependent current source?

Homework Equations

The Attempt at a Solution

The answer is -60. But I am getting 60. whenever It's power supplied doesn't it mean the current is entering from the negative end of the voltage ? like shown in the diagram? So shouldn't the negative signs cancel out? I am really confused.


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Answers and Replies

  • #2
Current flow is caused by electrons. Electrons originate from the negative terminal of a battery. But conventionally, the direction of current is taken in reverse. That is, external to the battery, it's from + to -, or in other words, from - to + inside the battery.

In the question, direction of current is from - to + inside the source. So the given polarities are proper and power delivered = VI= V1 * 3 Ix
= 10 * 3 * -2
= -60 units.