ShmoopTube

00:00

Thank you here's your shmoop du jour brought to you

00:05

by smashing guitars it's an old rock'n'roll tradition but we

00:09

can't afford to buy a new guitar all the time

00:10

so we just smash our air guitars like that Well

00:14

carrie is playing air guitar in her room imagining that

00:16

she's playing in front of a huge crowd She powers

00:19

through a sweet riff and the crowd goes wild Carrie

00:22

starts showboating swinging or guitar around around it flies off

00:26

the strap and smashes into the wall Talked about a

00:28

reality check She sorts through the pieces and notices that

00:32

the guitar pick up is a square coil of wire

00:36

Well maybe the broken guitar could be a science project

00:39

after all Science fair's coming up right Carrie flips open

00:42

her tax book looks for the words coil and finds

00:45

a page describing faraday's law According to this e m

00:48

f is induced in a coil within turns by a

00:52

change in magnetic floods In time carrie counts two hundred

00:57

turns in the coil and measures this side's as one

01:01

centimeter she places the coil in a uniform magnetic field

01:04

that points into the plane of the page Take a

01:08

look at this diagram right there Carrie increases be from

01:12

point Oh won t two point oh sixty in delta

01:15

t equals one s what imf is induced in the

01:19

coil and hear the potential answers one ten hundred thousand

01:24

when life hands you lemons while you make lemonade and

01:27

when life hands you a smashed guitar you make a

01:29

science project yeah we're pretty punk rock not so punk

01:33

rock that we have our own magnetic field generator though

01:36

kerry has quite the setup here right let's look at

01:39

magnetic flux First of all magnetic flux means the amount

01:43

of magnetic field passing through an area waken Think of

01:46

it like the density of a magnetic field in this

01:48

certain space so we can swap out b a for

01:52

the flocks which means our equation now shows the imf

01:55

equals the number of coils times the change in b

01:58

a over the change in time And since the area

02:01

is not changing we can bring that out Hang with

02:05

him Carrie increases the byfield from point Oh won t

02:09

two point oh sixty So the change in b equals

02:13

point Oh five tesla's Now we can plug in our

02:17

numbers and get back to rock in the house Mm

02:20

equals two hundred coils times one centimeter squared times point

02:24

oh five tesla's over one second Don't forget that with

02:28

an area of one centimeter squared it comes toh one

02:31

times ten to the negative forthe meters squared after we

02:34

do the math we find that the magnitude of imf

02:36

created is one mil eval So the correct answer is

02:39

a oh and one last thing way used a version

02:42

of faraday's law that cheats just a little bit faraday's

02:45

law expressed in this equation really should have a negative

02:48

sign in front of it negative sinus part of lens

02:51

law and it works to show the direction the current

02:54

needs to move in order to create a magnetic field

02:57

that opposes the change in floods But because this question

03:01

is really just dealing with the magnitude of voltage we

03:05

don't need to worry about the direction so don't tell

03:07

anyone but yeah we just broke the law one thrill

03:10

and remember to be careful with musical instruments They're meant

03:12

to make beautiful music that we don't want to be

03:15

smash guitars or broken drums that's or even a dented 00:03:18.22 --> [endTime] kazoo that matter

Full Transcript