How Do You Calculate Current and Power in Parallel Resistors?

[shemer77]

Homework Statement

2) 2 resistors, 42 and 64 ohms, are connected in parallel. The current through the 64 resistor is 3A. Determine the current in the other esistor and what is the total power supplied by the two resistors?

Homework Equations

The Attempt at a Solution

2) How could i possibly have enough info to do this one?

 

[mgb_phys]

1, Whats the overall resistance of 2 resistors in parallel (extend this to 3 resistors)?

 

[Ofey]

The resistance is not the same if the pieces are connected in parallel.

Resistors connected in parallel follow the law

1/(R.total)=1/(R.1)+1/(R.2)+1/(R.3)...

Where R.total is the total resistanse and R.1 is the resistanse of the first resistor, R.2 is the resistanse of the second resistor etc. etc.

 

[shemer77]

thanks figured that one out, can you help me with the second one?

 

[mgb_phys]

Assume the same voltage across both resistors.
Then V=IR for the known and I =V/R for the unknown.
(it should also be obvious how to skip a step)