the resistance of the cable is 582.9 ohms
we are given the length of the cable which is 3 km, of 1.5 mm in, the diameter and resistivity of copper which is 1.72 m
The formula we are referring to for calculating the resistance of the cable is
R = ρl/A.
As there are 19 strands of copper conductors, so the resistance will be
R = 19( ρl/A)
Here ρ is the resisitivity = 1.72 , l is the length = 3(1+0.05)*10³3= 3150 m
A=pie/4(1.5 x 10⁻³)^2 =1.766 x 10⁻⁶ =1.766 x 10^-6
Substituting the values in the formula we get
R = 19 ( 1.72*3150 )/1.766 x 10⁻⁶
= 582.9 ohm
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The source of the earth's magnetic field is found in the ;LIQUID MAGNETIZED IRON IN THE CORE OF THE EARTH. The earth's magnetic field is believed to be generated very deep down in the earth's core as a result of molten iron which it contains.

Explanation:
The acceleration due to gravity g is defined as

and solving for R, we find that

We need the mass M of the planet first and we can do that by noting that the centripetal acceleration
experienced by the satellite is equal to the gravitational force
or

The orbital velocity <em>v</em> is the velocity of the satellite around the planet defined as

where <em>r</em><em> </em>is the radius of the satellite's orbit in meters and <em>T</em> is the period or the time it takes for the satellite to circle the planet in seconds. We can then rewrite Eqn(2) as

Solving for <em>M</em>, we get

Putting this expression back into Eqn(1), we get




Explanation:
the force acting perpendicularly on unit area of surface
- unit=pascle .
Answer B is the correct pair.