An investigator places a sample 1.0 cm from a wire carrying a large current; the strength of the magnetic field has a particular value at this point. Later, she must move the sample to a 11.0 cm distance, but she would like to keep the field the same. Part A) By what factor must she increase the current?

Respuesta :

Answer: she will have to increase the factor of current by 11

Explanation: The mathematical relationship between the strength of the magnetic field (B) created by a current carrying conductor with current (I) is given by the Bio-Savart law given below

B=[tex]\frac{u_{0}I }{2\pi r}[/tex]

B=strength of magnetic field

I = current on conductor

r = distance on any point of the conductor from it center

u[tex]_{0}[/tex] = permeability of magnetic field in space

from the question, the investigator is trying to keep a constant magnetic field meaning B has a fixed value such as the constants in the formulae, the only variables here are current (I) and distance (r). We can get this a mathematical function.

by cross multipying, we have

B* 2πr=[tex]u_{0}[/tex]I

by dividing through to make I subject of formulae, we have that

I = [tex]\frac{B*2\pi r}{u_{0} }[/tex]

B, 2π and [tex]u_{0}[/tex] are all constants, thus

[tex]\frac{B*2\pi r}{u_{0} }[/tex] = k(constant)

thus we have that

I =kr (current is proportional to distance assuming magnetic field strength and other parameters are constant)

thus we have that

[tex]\frac{I_{1} }{r_{1} }[/tex]=[tex]\frac{I_{2} }{r_{2} }[/tex]

[tex]r_{1}[/tex]=1cm and [tex]r_{2}[/tex]=11cm

[tex]\frac{1_{1} }{1}[/tex]=[tex]\frac{I_{2} }{11}[/tex]

thus [tex]I_{2}[/tex]=11* [tex]I_{1}[/tex]

which means the second current is 11 times the first current