00:01
Okay, so we're doing in chapter 29 problem 11.
00:04
So this says in the region of space, a magnetic field points in the positive x direction.
00:10
So call this positive x -b field, and the magnitude is given as an initial magnitude b -not plus b times x, with b -not and b greater than 0 when x is greater than 0.
00:30
So let's call this our xy plane.
00:40
So our origins over here.
00:42
Cool.
00:43
So it also says a flat coil, so it equals one with an area.
00:50
It moves with uniform speed v from right to left with a plane that always put the indicator in the field.
00:56
So let's draw this here and v is moving this way towards the origin.
01:04
Cool.
01:05
So now it says part a.
01:07
What is the induced ems of this guy? so faraday's law of course says the induced emf is given as a negative change magnetic flux.
01:17
It's a function of time or a rate time.
01:20
So now we got to figure out what is the flux to figure this out.
01:26
So a flux is given as the magnitude of b times the cross -sectional area.
01:35
Okay.
01:36
A b is a function of x, right? so this flux is a flux.
01:39
Changes in a function of x.
01:40
So this is b not plus v times x times the area.
01:47
So now when we take the derivative, defy v d t is a b not that has no x dependence so that's just gone.
02:00
Okay, so then we have a times little b times d x d t but d x d t is just the velocity that this is changing, right? so this is a, b times v.
02:15
But v is in the negative direction.
02:18
So this...