# A rectangular block of copper has sides of length 10 cm, 20cm, and 40 cm. If the block is connected to a 6V sourceacross two of its opposite faces, what are (a) the maximum currentand (b) the minimum current that the block can carry?

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A rectangular block of copper has sides of length 10 cm, 20cm, and 40 cm. If the block is connected to a 6V sourceacross two of its opposite faces, what are (a) the maximum currentand (b) the minimum current that the block can carry?

2021-04-18
given
length L = 40 cm
= 0.40 m
=0.20 m
thickness t = 10 cm
= 0.10 m
Voltage V = 6.0 V
area A = (L)(B)
we want to find the current
we have given voltage (V) and sides of the rectangular box
we can proceed with ohms law V=(I)(R)
here resistance (R) is unknown
from theory when the length and area are given we have the equation for resistance as
R = ?(L/A)
where ? is the specific resistance of thematerial, (L) is the length, and (A) is the area of the
rectangular box
as the rectangular box has three sides we havethree values of (L/A)
with 0.6 m, 0.22 m, 0.44 m
a) from those values of (L/A) choose minimumvalue of (L/A) and substitute in $$\displaystyle{I}_{{\max}}={\frac{{{V}}}{{{R}_{{\min}}}}}$$
$$\displaystyle={\frac{{{V}}}{{{\left(?{\frac{{{L}}}{{{A}}}}\right)}_{{\max}}}}}$$
b) from those values of (L/A) choose maximumvalue of (L/A) and substitute in
$$\displaystyle{I}_{{\min}}={\frac{{{V}}}{{{R}_{{\max}}}}}$$
$$\displaystyle={\frac{{{V}}}{{?{\left({\frac{{{L}}}{{{A}}}}\right)}_{{\max}}}}}$$