b) between poles M1 and M2
Explanation:
From the expression, we can deduce that r is the distance between two magnetic poles M1 and M2.
The law of attraction between two magnetic poles states that:
<em> the force of attraction or repulsion between two magnetic poles is a function of the product of the strength of the magnetic poles and the square of the distance between the pole</em>s
Mathematically:
FM = K 
here r is the distance between the poles
FM is the magnetic force between the poles
M1 is the strength of the first magnetic pole
M2 is the strength of the second pole
K is the magnetic field constant
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magnetic pole brainly.com/question/2191993
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Answer:
20 N
Explanation:
In air, the normal force is equal to the weight.
∑F = ma
N − mg = 0
N = mg
Submerged in water, the normal force is equal to the weight minus the buoyant force:
∑F = ma
B + N − mg = 0
N = mg − B
Plugging in values:
80 N = 100 N − B
B = 20 N