Without speeding up it would take 5 1/3 seconds.. not sure if it speeds up in the question?
Answer:
The magnetic field is
Direction is inward
Step-by-step explanation:
The diagram for this question is shown on the first uploaded image
From the question we are told that
The radius of BC is 
The radius of DA is 
The length of CD is 
The length of AB is 
The current is 
The magnetic field is mathematically represented as

![B = \frac{\mu_o I}{4 \pi } [ \frac{\theta_{DA}}{r_{DA}} + \frac{\theta_{BC}}{r_{BC}}+ \frac{\theta_{CD}}{r_{CD}}+\frac{\theta_{AB}}{r_{AB}}]](https://tex.z-dn.net/?f=B%20%3D%20%20%5Cfrac%7B%5Cmu_o%20I%7D%7B4%20%5Cpi%20%7D%20%5B%20%5Cfrac%7B%5Ctheta_%7BDA%7D%7D%7Br_%7BDA%7D%7D%20%2B%20%5Cfrac%7B%5Ctheta_%7BBC%7D%7D%7Br_%7BBC%7D%7D%2B%20%5Cfrac%7B%5Ctheta_%7BCD%7D%7D%7Br_%7BCD%7D%7D%2B%5Cfrac%7B%5Ctheta_%7BAB%7D%7D%7Br_%7BAB%7D%7D%5D)
Where

Where 

so
![B = \frac{\mu_o I}{4 \pi } [ \frac{\frac{2\pi}{3} }{0.20} - \frac{\frac{2\pi}{3}}{0.30}}+ \frac{0}{0.10}+\frac{0}{0.10}]](https://tex.z-dn.net/?f=B%20%3D%20%20%5Cfrac%7B%5Cmu_o%20I%7D%7B4%20%5Cpi%20%7D%20%5B%20%5Cfrac%7B%5Cfrac%7B2%5Cpi%7D%7B3%7D%20%7D%7B0.20%7D%20-%20%5Cfrac%7B%5Cfrac%7B2%5Cpi%7D%7B3%7D%7D%7B0.30%7D%7D%2B%20%5Cfrac%7B0%7D%7B0.10%7D%2B%5Cfrac%7B0%7D%7B0.10%7D%5D)

The direction is into the page
This because the magnitude of the magnetic field due to arc BC whose direction is outward is less than that of DA whose direction is inward
This is because according to Fleming's Left Hand Rule the direction of current is perpendicular to the direction of magnetic field so since current in arc BC and DA are moving in opposite direction their magnetic field will also be moving in opposite direction
Only D is correct, it intersects at 90 degrees so it cant be obtuse or acute and never intersecting would be parallel lines <span />
Answer:
B
Step-by-step explanation: