when voltage source is connected across an ideal inductor, the current through it is limited by self induced EMF( N.d(phi)/dt).. This EMF opposes its cause by Lenz's law.
When steady dc supply is connected, there is no change of flux and hence no induced EMF is developed and inductive reactance offered to steady DC supply is zero.
At the same time this induced EMF is proportional to rate of change of magnetic flux/voltage, hence the inductive reactance offered is also proportional to frequency of voltage source.
Answer:
Magnetic materials have many spinning, unpaired electrons.
Explanation:
Any moving electric charge creates a magnetic field, also electrons since they spin and move around the nucleus. However, if two electrons are paired on the same orbital they always spin in opposite directions that causes their magnetic field to cancel out. Even if there are unpaired electrons in some atoms and these atoms act as small magnets, the magnetic field of the neighbouring atoms can have different directions and they also cancel out each other. Only presence of a large number of unpaired electrons in a material can create a significant magnetic field. This is the root part of the definition of magnetic properties of material.
Answer:
It goes upward and downward
Explanation:
The way the man is moving the string indicates it goes movement of up and sown, I believe the straight line(B) is a distraction.
The acceleration should be a gain of 2 km/h per second
(a) Differentiate the position vector to get the velocity vector:
<em>r</em><em>(t)</em> = (3.00 m/s) <em>t</em> <em>i</em> - (4.00 m/s²) <em>t</em>² <em>j</em> + (2.00 m) <em>k</em>
<em>v</em><em>(t)</em> = d<em>r</em>/d<em>t</em> = (3.00 m/s) <em>i</em> - (8.00 m/s²) <em>t</em> <em>j</em>
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(b) The velocity at <em>t</em> = 2.00 s is
<em>v</em> (2.00 s) = (3.00 m/s) <em>i</em> - (16.0 m/s) <em>j</em>
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(c) Compute the electron's position at <em>t</em> = 2.00 s:
<em>r</em> (2.00 s) = (6.00 m) <em>i</em> - (16.0 m) <em>j</em> + (2.00 m) <em>k</em>
The electron's distance from the origin at <em>t</em> = 2.00 is the magnitude of this vector:
||<em>r</em> (2.00 s)|| = √((6.00 m)² + (-16.0 m)² + (2.00 m)²) = 2 √74 m ≈ 17.2 m
(d) In the <em>x</em>-<em>y</em> plane, the velocity vector at <em>t</em> = 2.00 s makes an angle <em>θ</em> with the positive <em>x</em>-axis such that
tan(<em>θ</em>) = (-16.0 m/s) / (3.00 m/s) ==> <em>θ</em> ≈ -79.4º
or an angle of about 360º + <em>θ</em> ≈ 281º in the counter-clockwise direction.
