An iron bar can be made magnetic when its magnetic domains line up.
<span>That statement is false. An upward fold on a rock is acalled an anticline
a typical anticline is convex up in which the hinge or crest is located where the curvature is the greatest and the limbs are the side of the fold that dip away from the hinge</span>
Answer
given,
B = 2 T
time = 20 s
Radius = R = 400 mm
L= 300 mm
apply the formula for magnetic energy density
![\eta_0 = \dfrac{energy}{volume}](https://tex.z-dn.net/?f=%5Ceta_0%20%3D%20%5Cdfrac%7Benergy%7D%7Bvolume%7D)
![\eta_0 = \dfrac{B^2}{2\mu}](https://tex.z-dn.net/?f=%5Ceta_0%20%3D%20%5Cdfrac%7BB%5E2%7D%7B2%5Cmu%7D)
![\eta_0 = \dfrac{2^2}{2\times 4 \pi 10^{-7}}](https://tex.z-dn.net/?f=%5Ceta_0%20%3D%20%5Cdfrac%7B2%5E2%7D%7B2%5Ctimes%204%20%5Cpi%2010%5E%7B-7%7D%7D)
energy density = 1.59 x 10⁶ J/m³
Now , in the cylinder ,
Energy = energy density x volume
E = 1.59 x 10⁶ x π x r² x h
E = 1.59 x 10⁶ x π x 0.4² x 0.5
E = 4 x 10⁵ J
now, average rate of energy dissipated
rate of dissipation of energy = Energy/time
= 4 x 10⁵ /20
= 2 x 10⁴ W
the average rate at which energy is dissipated is 2 x 10⁴ W
Answer: Delta U = 30 - 80; -50 jules
Explanation:
The system is losing 80 J, but it is also gaining 30 J because the surroundings are doing work on it. So the net change in energy is -50 J