Answer:
0.546 [tex]\hat k[/tex]
Explanation:
From the given information:
The force on a given current-carrying conductor is:
[tex]F = I ( \L \limits ^ {\to } \times B ^{\to})\\ \\ dF = I(dL\limits ^ {\to } \times B ^{\to})[/tex]
where the length usually in negative (x) direction can be computed as
[tex]\L ^ {\to } = -x\hat i \\dL\limits ^ {\to }- dx\hat i[/tex]
Now, taking the integral of the force between x = 1.0 m and x = 3.0 m to get the value of the force, we have:
[tex]\int dF = \int ^3_1 I ( dL^{\to} \times B ^{\to})[/tex]
[tex]F = I \int^3_1 ( -dx \hat i ) \times ( 4.0 \hat i + 9.0 \ x^2 \hat j)[/tex]
[tex]F = I \int^3_1 - 9.0x^2 \ dx \hat k[/tex]
[tex]F = I (9.0) \bigg [\dfrac{x^3}{3} \bigg ] ^3_1 \hat k[/tex]
[tex]F = I (9.0) \bigg [\dfrac{3^3}{3} - \dfrac{1^3}{3} \bigg ] \hat k[/tex]
where;
current I = 7.0 A
[tex]F = (7.0 \ A) (9.0) \bigg [\dfrac{27}{3} - \dfrac{1}{3} \bigg ] \hat k[/tex]
[tex]F = (7.0 \ A) (9.0) \bigg [\dfrac{26}{3} \bigg ] \hat k[/tex]
F = 546 × 10⁻³ T/mT [tex]\hat k[/tex]
F = 0.546 [tex]\hat k[/tex]
