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# Answer for Electromagnetism Questions?

Please give me the answers of following questions with reasons as soon as possible;

Q1)- Can the path of integration around which we apply Ampere's Law pass through a Conductor?

Q2)- A long straight wire of radius R carrier a steady current i. How does the magnetic field generated by this current depend on R? consider both outside and inside the wire?

Q3)- Does equation B= UxIxn hold for a solenoid of cross-sectional area of square shape?

Q4)- A circular loop of wire lies on the floor of the room in which you are sitting. it carries a constant current "i" in a clockwise sense, as viewed from above. what is the direction of magnetic dipole moment of this current loop?

Q5)- Equation B=(U*I)/2*pi*R) suggests that a strong magnetic field is setup at points near a long wire carrying a current, since there is a current "i" and magnetic field B, why is there not a force on the wire in accord with the equation F = i (L*R)?

Q6)- The 25kv electron given in diameter at the screen 5.6x10^14 (5.6 x 10 power 14) electrons arriving each second. calculate the magnetic field produced by the beam at a point 1.5 mm from the axis of beam??(hint: Biot-savarat law)

Thanks

### 1 Answer

- u.n. oLv 59 years agoFavorite Answer
Q! - yes.

Q2 - assume current density is uniform in wire (this will be the case for dc). Then current inside wire is given by B*2pi*r = u0i*(r/R)^2 up to and including r = radius R. So B = 0 at the wire's center, B = u0*i*r/(R^2) and B = u0i/(2pi*R) on the surface. u0 = 1.26e-6 SI.

Beyond r=R, B*2pi*r = u0i or B = u0i/(2pi*r).

Q3 - ?

Q4 - don't remember dipole moment

Q5 - because force = il x B where l and B are vectors, and the cross-product of two aligned vectors 0.

Q5 - screen? Need to know length of the electron beam. If infinite, can use Ampere's law.