1. The problem statement, all variables and given/known data A conductor consists of a circular loop of radius R and two long, straight sections as shown in the figure. The wire lies in the plane of the page and carries a current I. (a) What is the direction of the magnetic field at the center of the loop? (b) Find an expression for the magnitude of the magnetic field at the center of the loop. (Use any variable or symbol stated above along with the following as necessary: μ0 and π.) 2. Relevant equations Biot-Savart law Ampere's Law? 3. The attempt at a solution For (a), I'm not 100% sure if this reasoning is right, but using a right-hand rule, I pointed my thumb in the direction of the current, which is clockwise, then checked which way my fingers were curling, which would be kind of towards the center of the loop and thus into the page. It doesn't really make 100% sense to me, but it seems to produce the right answer. For (b), I'm really confused about one thing. The solution says that the total magnetic field is the combination of the field due to the long straight wire and the field due to the circular loop. How are these any different at all? If you use the Biot-Savart law, you get a certain answer (μI/2R). But supposedly the answer is that plus the same answer with π on the bottom. So I guess I have the field from the circular loop. How do you get the other one?