Checking two sets of physics problems

[matt222]

I Have two set of Qs i worked throu. & i am not sure of my works
am i on the right tuck

 

[OlderDan]

I Have two set of Qs i worked throu. & i am not sure of my works
am i on the right tuck

In #1, your comment (average flux) is not correct. It is not an average, it is a difference.

In #2, what is the basis of the equation you used for E?

 

[matt222]

So #1 is right, only the comment (average flux) is wronge??

in #2 i used farady's law( E 2pi r= -the rate of change of flux), for induced electric field:

E (2pi r)= -(pi R^2 dB/dt)/2r

E=1/2r* dB/dt *R^2

this is E

 

[OlderDan]

So #1 is right, only the comment (average flux) is wronge??

in #2 i used farady's law( E 2pi r= -the rate of change of flux), for induced electric field:

E (2pi r)= -(pi R^2 dB/dt)/2r

E=1/2r* dB/dt *R^2

this is E

In #1 you also failed to include the number of turns of wire in the coil. Other than that it is good.

You need to take another look at Faraday's law. The flux involved is the flux through the closed path of the E•ds integral.