Question

Problem 28.15 9of15 Part A A long pair of insulated wires serves to conduct 28 4 A of d current to and from an instrument A third wire is placed in the plane of the two wires shown in the figure paralel and jst to the right (Figure 1) f R carries 24.9 A upward what force per meter of length does t exert on each of the other cener wies? Assume it s 28m fron the nearest wire, certe lo Express your anawer to twoe significent figures and incude the appropriate units ?· 100143 Figure 1o1 X Incorrect, Try Again; 5 attempts remaining Part ? Express your answer to two sVfcant "gures and include the approprate Value Units 2.8 mm

Answer 1

From the image we can see that the third wire carring I^' = 24.9 n current We know that if two wires carry current in the same direction then They attract each other and the force per unit length is given by F = mu_0/4pi times 2I I^'/r_0 whole r rightarrow centre to electric distance Now, for near wire we here F_near/l_near = mu_0/4pi times 2I I^'/r Now, I = 23.4 A: I^' = 24.9 A r = 2.8 mm = 2.8 times 10^-3 m so, F_near/l_near = 10^-7 times 2 times 25.4 times 24.9/2.8 times 10^-3 = 45.17 times 10^-3 N/m \r\n or F_near/l_near = 0.045 N/m Ans and force is attractive B) Similarly for the for wire F_for/l_for = mu_0/4pi times 2I I^'/r^' Here r^' = 2r = 2 times 2.8 mm = 2 times 2.8 times 10^-3 m So, F_for/l_for = 10^-7 times 2 times 25.4 times 24.9/2 times 2.8 times 10^-3 F_for/l_for = 0.0225 N/m