Answer:
![B_(net) = (2\sqrt2 \mu_0 i)/(\pi d)](https://img.qammunity.org/2020/formulas/physics/college/g2qrff1oj2p4nyfoiwp4d81zm4zotjpoxa.png)
Step-by-step explanation:
Magnetic field due to straight current carrying wire is given by the formula
![B = (\mu_0 i)/(4\pi r)(sin\theta_1 + sin\theta_2)](https://img.qammunity.org/2020/formulas/physics/college/qg8yqn2eql3gefgxj87lypy7rbm13ailxg.png)
now we will have for one side of the square at its center position given as
![B = (\mu_0 i)/(4\pi ((d)/(2)))(sin45 + sin45)](https://img.qammunity.org/2020/formulas/physics/college/f67r08cq8qsg02ljeraeso1rh5wavwsjxk.png)
![B = (2\sqrt2 \mu_0 i)/(4 \pi d)](https://img.qammunity.org/2020/formulas/physics/college/8mc85p1npsqnxldora3mlnjt21hmdfz42j.png)
now for the we have for complete square loop it will become 4 times of the one side
![B_(net) = 4 B](https://img.qammunity.org/2020/formulas/physics/college/i5o30u4jeq4qvng9x2g3vu2wfpbndv6ear.png)
![B_(net) = 4 (2\sqrt2 \mu_0 i)/(4 \pi d)](https://img.qammunity.org/2020/formulas/physics/college/pvtnqzgqa855tpowldhrdiinvpa0dsbw4f.png)
![B_(net) = (2\sqrt2 \mu_0 i)/(\pi d)](https://img.qammunity.org/2020/formulas/physics/college/g2qrff1oj2p4nyfoiwp4d81zm4zotjpoxa.png)