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:
   θ = 28.9
Explanation:
For this exercise let's use the law of refraction
           n₁ sin θ₁ = n₂ sin θ₂
where we use index 1 for air and index 2 for water where the fish is
         sin θ₂ = n₁ / n₂ sin θ₁
in this case the air repair index is 1 and the water 1.33
we substitute
         sin θ₂ = 1 / 1.33 sin t 40
         sin θ = 0.4833
          
         θ = sin⁻¹ 0.4833
         θ = 28.9
 
        
             
        
        
        
Answer:
 the formulae is f = mg = vpg
 
        
             
        
        
        
The correct answer is B.Antartica and Australia were one landmass millions of years ago.
 
        
             
        
        
        
Explanation:
Given that,
Mass of the rock climber, m = 90 kg
Original length of the rock, L = 16 m 
Diameter of the rope, d = 7.8 mm
Stretched length of the rope, 
(a) The change in length per unit original length is called strain. So,

(b) The force acting per unit area is called stress. 

(c) The ratio of stress to the strain is called Young's modulus. So,

Hence, this is the required solution.