One wire has a cross-sectional area of 1,250 cmil and a resistance of 7 ohms. A second piece of wire, identical except for cross-sectional area, has a resistance of 10 ohms. Determine what the cross-sectional area of this second wire is. (Cross-sectional area and resistance are inversely proportional.)

875 cmil

Explanation:

Cross section area of wire=

Resistance of wire,

We have to find the cross sectional area of second wire

We know that

According to question

....(1)

...(2)

Equation (1) divided by equation (2) then, we get

Hence, the cross- sectional area of second wire=875 cmil

c) up is the direction the magnetic force is acting on the charge.

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west