Question

a light bulb uses 40.0 Wof power when connected to a 110 V (DC) outlet. if the same bulb is connected to a european 220 V outlet, how much power will the bulb use?
(hint: what is the resistance of the bulb?)(unit=W)

Answer 1

Hi there. Do you have any idea which formula we should use?

Hint: we want something that can help us calculate the power and we have the voltage and resistance (amps)

Answer 2

idk the formula

Answer 3

Have you seen this formula before?

Power = voltage * current

P = IV

Where power is in watts
Current is A
And voltage is V

Answer 4

P= IV=I^2R=v^2/R

Answer 5

AND YES IVE SEEN THAT FORMULA

Answer 6

Yes, but we only need to select one of them :)

Answer 7

PERFECTO
Let's solve this
It's ez pz

Answer 8

So we know a light bulb uses 40.0 W of power and is connected to 110 V outlet

Can you plug that into the formula and calculate the resistance of the bulb?

Answer 9

just do it for me please

Answer 10

so wat is the answer

Answer 11

Unfortunately I can't do it for you, that would defeat the whole purpose of you being able to learn

It'll take you less than two minutes to solve it if you work with me

Answer 12

smt

Answer 13

P = I * V
They gave us P = 40.0 W
And V = 110 V

Can you solve for I?

Answer 14

=302.5

Answer 15

How'd you get that mhmm

Answer 16

its wrong

Answer 17

when a certain amount of current flows through a resistor, it uses 3.00 w of power. if the current doubles, how much power will the resistor use? (Hint: R stays the same. how does P depend on I and R?)(unit=W)

Answer 18

wat abou this one

Answer 19

Did you find the correct answer then?

40 W = I * 110V

Solve for I
The units will be A

Once you find I, you just multiply by 220 V to get the power

Answer 20

=66550

Answer 21

?

Answer 22

uhhh wait

Shouldn't we be using the P= V^2/R formula

I accidentally confused current with resistance

Answer 23

40 = (110)^2 / R

Solve for R

R = (110)^2 / 40
R = ?

Answer 24

302.5

Answer 25

the answer is 0.852

Answer 26

How did you get 0.852?

302.5 ohms is the resistance

Now for what we're trying to find
P = V^2/R

We know that V = 220
And R = 302.5

So what is P=?

Answer 27

=160

Answer 28

And that's your answer
160 W