What current is needed in the solenoid’s wires?

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To cancel the Earth's magnetic field in a solenoid experiment, a specific current is required based on the solenoid's dimensions and the Earth's magnetic field strength. The solenoid has a diameter of 1.0 m, a length of 4.0 m, and 5000 turns of wire. Using Ampere's law, the necessary current can be calculated as approximately 25.5 milliamp (0.0255 A) when using the Earth's magnetic field strength of 5 x 10^-5 T. The calculations involve the magnetic permeability and the relationship between magnetic field strength, current, and the number of turns in the solenoid. Ensuring the correct values are used in the formula is crucial for accurate results.
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Homework Statement


A researcher would like to perform an experiment in zero magnetic field, which means that the field of the Earth must be cancelled. Suppose the experiment is done inside a solenoid of diameter 1.0 m, length 4.0 m, with a total of 5000 turns of wire. The solenoid is oriented to produce a field that opposes and exactly cancels the field of the earth. What current is needed in the solenoid’s wires?


Homework Equations


∑B ∆length = (µ0)I


The Attempt at a Solution


B = 5 * 10^-5 T
length = 4 m
radius = 0.5 m


i = [4*(5*10^-5)]/(5000*2*pie*0.5)
i = 1.27*10^-8

have i done this correctly at all??
 
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using Ampere's law the magnetic field ina solenoid will be given by

B= magnetic permeability x current i x number of turns N / length L

and for cancelling Earth's magnetic field, the current needed is

i = B x L / N x magnetic permeability

= 0.4x10^-4 x 4 / 5000x 4 pi x 10^-7 = 2.55 x 10^-2 Amp

= 25.5 milli amp.

Or is this correct??
 
That would look correct but I don't know the strength of Earth's magnetic field off-hand
 
my book says that the Earth's magnetic field strenght is 5 *10^-5...so would i use that instead of the .4 x 10^-4??
 
Yes.
 
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