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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In the part of the spectrum our eyes can detect (a spectrum is an arry of entities, as light waves or particles, ordered in accordance with the magnitudes of a common physical property, as wavelength or mass) Hope this helps you :D
W=20 e(-kt)
A. Rearranging gives k= -(ln(w/20)/t
Substituting w= 10 and solving gives k=0.014
B. Using W=20e(-kt). After 0 hours, W=20. After 24 hours, W=14.29g. After 1 week (24x7=168h) W=1.9g
C. Rearranging gives t=-(ln(10/20)/k. Substituting w=1 and solving gives t=214 hours.
D. Differentiating gives dW/ dt = -20ke(-kt). Solving for t=100 gives dW/dt = 0.07g/h. Solving for t=1000 gives 0.0000002g/h
E. dW/dt = -20ke(-kt). But W=20e(-kt) so dW/dt = -kW