Divide the long wire in small segments. The field due to one segment can be found from Biot- Savart law.
dB=(uo/4pi) Idlxr/r^3. In this expression if we take vector r perpendicular to current element , the cross product in the expression shows that the direction of B is perpendicular to vector r and from symmetry it can be said that field line is circular around the wire segment. This is true for all segment ,because in infinitely long wire all segments are equivalent . Thus, magnetic field lines are concentric around a long straight wire.
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Answer:
(d) I and III
Explanation:
Motion of the 1st light ball


I. Since the heavier starts with an initial velocity v0, and both balls end up traveling the same distance s. From the 2 motion equation above we can conclude that their time must be different
II. Both balls are affected by the same gravitational acceleration g
III. Velocity before the impact of the light ball

And the heavy ball

Since they have the same acceleration g and distance s. But the heavy ball has an initial push. It would end up with a larger speed.
<h2>Answer: The Medium </h2><h2 />
<u>The medium is the main factor that differentiates a mechanical wave from an electromagnetic wave,</u> since the first can not propagate without its existence, while the second can propagate regardless of whether the medium exists or not.
In addition, it is the medium that will define, the propagation speed of the wave, according to its specific physical characteristics.
should be 1
Explanation:
because what do you use in class and has a lever
d through a railroad track