Answer:
The formula comes from Lorentz force law which includes both the electric and magnetic field. If the electric field is zero, the force law for just the magnetic field is <u>F=q(ν×B</u>) . Here, F is force and is a vector because the force acts in a direction. q is the charge of the particle. v is velocity and is a vector because the particle is moving in some direction. B is the magnetic flux density.
We can derive an expression for the magnetic force on a current by taking a sum of the magnetic forces on individual charges. (The forces add because they are in the same direction.) The force on an individual charge moving at the drift velocity vd. Since the magnitude of B is constant at every line element of the loop (circle) and it dot product with the line element is B dl everywhere, therefore
∮B dl=μ0 I
B ∮dl=μ0 I
B 2πr=μ0 I
B=μ02πr Id=μ0/4π I dl×rr3
Since, r can be written as r=(rcosθ,rsinθ,z) and dl as dl=(dl,0,0) And now, if we take the cross product we would get
dl×r=−z dlj^+rsinθk^
and therefore the magnitude of dB is equal to
dB=μ0/4π I |dl×r|/r3=μ0/4π I z2+r2sin2θ−−−−−−−−−−√dl/r3
Thus, magnetic field is depending on r,θ,z.
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Answer:19ohms
Explanation:
equivalent resistance=5+2+12
equivalent resistance=19ohms
Answer:
Angular momentum, 
Explanation:
It is given that,
Radius of the axle, 
Tension acting on the top, T = 3.15 N
Time taken by the string to unwind, t = 0.32 s
We know that the rate of change of angular momentum is equal to the torque acting on the torque. The relation is given by :

Torque acting on the top is given by :

Here, F is the tension acting on it. Torque acting on the top is given by :





So, the angular momentum acquired by the top is
. Hence, this is the required solution.
A water wave is an example of a mechanical wave. A wave that can travel only through matter is called a mechanical wave.