Question

If you have a 45.0 V battery connected to a 10.0 Ωresistor and a 500.0 Ω

resistor in series, what will be the total power in the circuit?

45.0 W
13.5 W
4.50 W
3.97 W

Answer 1

im not quite sure. @TheSmartOne

Answer 2

please explain, i wanna make sure i understand it! (:

Answer 3

Of course! So in circuit where the resistors are connected in series, what would be the total resistance?

Do we add the sum of the resistors (R1+R2) or do we have to do the sum the inverse of the resistance (1/R1 + 1/R2)

Answer 4

you would add them! (:

Answer 5

Bingo! In parallel circuits we would do the sum of the inverse

So what is the sum of the resistors in this series circuit?

Answer 6

What formula would we use? We want power and we have the resistance and voltage

Answer 7

we would use I=V/R ?

Answer 8

That would give us current. We want the power!

Answer 9

oh im sorry i mean the P= V* I

Answer 10

Once again

Power = voltage * current

We could calculate current from the previous formula you mentioned and then plug it in here

But if you look at the chart, there is a direct formula that basically plugs in the two formulas you mentioned

P = IV
I = V/R

Plug in the second into the first

P = V^2/R

You can find this one in the top left hand corner of that image I shared

Answer 11

That's how you get that formula from the formula you mentioned ^

Answer 12

But does that make sense? That way we don't have to calculate the current so it saves us some time and steps :)

Answer 13

ohh okay, so you combine them together! yes that does make sense. could i solve it and you can double check it?

Answer 14

Absolutely! Go for it :)

Answer 15

it would be 45.0 ?

Answer 16

Can you show me your work so I can see where you might have made a mistake

Answer 17

well i used 10 as the resistance but i think i may have done that wrong

Answer 18

You forgot to add the 500 ohms resistance

Answer 19

you add them together right so would it be 510 ?

Answer 20

Yup!

Answer 21

yes! i think i got it

Answer 22

Well done!!

Answer 23

thank you so much! seriously you have been very helpful. I have a few more questions, i you may check them for me?

Answer 24

if you*

Answer 25

For sure, anytime!