- #1
paul11273
- 156
- 0
I can't seem to wrap my head around this question. Any help would be great.
A coil consists of 20 turns, with a 10cm radius (all turns are uniform).
It rotates uniformly around the z-axis at an angular speed of: w=20 rad/s
A uniform magnetic field passes along the x-axis with a magnitude of B=0.3T.
Find:
a) The induced emf at any time moment t>0 if at t=0 the coil was in the yz plane.
b) Direction of the induced current at t=0.
First, b) is easy. The answer is zero, there is no induced current at t=0 because the coil is not moving through the field yet.
For a) I started with this:
E=-N*(dB flux/ dt) (where E=emf)
Since B flux=BAcos(theta)=BAcos(wt) is sub this into get:
E = -NBAcos(wt) d/dt
E = NBAwsin(wt) then sub in the given values for N, B, w and calculate A=pi*r^2
E = 20*.3*pi(.1m)^2*20*sin(20t)
E = 1.2pi*sin(20t) is my final answer.
Is this correct? Someone in my class has E=4pi*sin(20t)
Can someone check my answer and offer some advice?
Thanks in advance.
A coil consists of 20 turns, with a 10cm radius (all turns are uniform).
It rotates uniformly around the z-axis at an angular speed of: w=20 rad/s
A uniform magnetic field passes along the x-axis with a magnitude of B=0.3T.
Find:
a) The induced emf at any time moment t>0 if at t=0 the coil was in the yz plane.
b) Direction of the induced current at t=0.
First, b) is easy. The answer is zero, there is no induced current at t=0 because the coil is not moving through the field yet.
For a) I started with this:
E=-N*(dB flux/ dt) (where E=emf)
Since B flux=BAcos(theta)=BAcos(wt) is sub this into get:
E = -NBAcos(wt) d/dt
E = NBAwsin(wt) then sub in the given values for N, B, w and calculate A=pi*r^2
E = 20*.3*pi(.1m)^2*20*sin(20t)
E = 1.2pi*sin(20t) is my final answer.
Is this correct? Someone in my class has E=4pi*sin(20t)
Can someone check my answer and offer some advice?
Thanks in advance.