Watts from ohms one line

[Rjv0858]

I'm studying for my masters test and I can't find for the life of me how they got the answer for this question. If someone can explain it to me it would be greatly appreciated. Question #50 in the picture.

 

[hbiss]

Look at what S1 and S3 do when they are closed.


-Hal

 

[Rjv0858]

I see that , what answer did you come up with?

 

[jim dungar]

I see that , what answer did you come up with?

Hint. My answer was based on only two resistors.

 

[Rjv0858]

I'm really just learn how to do solve the the question, so if someone could teach me how and why we are only using two resistors

 

[Sea Nile]

I'm really just learn how to do solve the the question, so if someone could teach me how and why we are only using two resistors

The other resistors are bypassed because there in a path around them.

Imagine a light bulb with the terminals shorted. In series with another load so ther breaker won't trip. That light would never be a factor to the resistance of the circuit

 

[Rjv0858]

The book says the answer is 500 watts, please explain how they got that.

 

[Little Bill]

You have to solve for resisters in parallel and series. Then use ohms law to solve.

 

[Sea Nile]

The book says the answer is 500 watts, please explain how they got that.

What is the formula for resistance of parallel loads.

 

[Rjv0858]

Thats why I am asking the question? Can someone please just tell me how to do it? Thanks

 

[Sea Nile]

You can do this, just think about it and put in the work

 

[Little Bill]

Thats why I am asking the question? Can someone please just tell me how to do it? Thanks

I'll give you one hint. Anytime you have two equal resisters in parallel you can solve without using the formula as the answer would be half the value of the resisters. Example: (1) 40ohm resister in parallel with another 40ohm resister would be 20ohms.

 

[Rjv0858]

Great thank you , thats what I was confused about.

 

[LarryFine]

We're not trying to be jerks when we don't just give answers to questions like this because we (A) want to get a feel for how much you do know, and (B) because you learn so much more by figuring it out.

Start with finding which two variables you know to choose a formula to find the solution. Do you know what the total resistance is with the switches closed as explained?

E = I x R
P = E x I

 

[Little Bill]

Here is a chart called a "pie chart" with electrical formulas.

 

[Rjv0858]

Yes I know all about that , what I didn't know is how to find total resistance of parallel loads. The equation made no sense to me , now I understand it. Thanks for the help

 

[Rjv0858]

Total resistance of the line diagram 50 ohms?

 

[Dsg319]

Yes I know all about that , what I didn't know is how to find total resistance of parallel loads. The equation made no sense to me , now I understand it. Thanks for the help

Your uglys book will have some actual examples showing the math.

 

[Rjv0858]

Your uglys book will have some actual examples showing the math.

Going to purchase an uglys book immediately, thanks

 

[Sea Nile]

Get yourself an ugly's book, if you don't already have one. It has all the formulas and they have them at the hardware store.