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Isaav physics question help

I've got these questions as hw and am struggling:
The shape in Figure 1 is made of wire with resistivity 1.20×10−6 Ωm and cross-sectional area 0.200mm^2. It consists of straight lines and a semicircle.

A 2D wire shape. On the right is a semicircle, connected to two horizontal sections, each 10.0 cm long and 10.0 cm apart, ending in terminals labelled A and B. Another wire connects the middle of the bottom horizontal wire to the right of the top horizontal wire where it meets the semicircle. This wire has a 5.00 cm long vertical section and the rest is diagonal.
Figure 1: A wire shape.

1) What is the resistance between points A and B?

2) A voltage source of emf 100mV and negligible internal resistance is connected between A and B.

What is the current in the semicircular part of the shape?
Any help would be much appreciated 🙏
Reply 1
For question 1 - I worked out all the resistances for each section of wire in the diagram. Im going to add in a few points to the diagram to help me explain which bits are which: the join between the straight wire, the semi circle and the diagonal wire is C, the join between the other straight wire and semi circle is D and the join between the branch going through the middle and the straight line is E.

The resistance from B to C is 0.6 (note the measurements are in cm not m) which is just the distance multiplied by R/L in the previous part of the question. The resistance between A and E is 0.3, the resistance of the diagonal branch between E and C is 0.3sqrt(2) + 0.3 (this is considering the triangle with two sides 5cm, doing pythagoras to get hypotenuse 5sqrt(2) cm) and the circular branch between E and C is 0.3pi + 0.3. (This is done by considering half circumference with diameter 10 =5pi cm).
Now all the resistances have been worked out they must be combined. Using the formula for parallel branches 1/R1 + 1/R2 = 1/R total, the resistance of the two branches is 0.4575… and then add this onto the two other resistances of the wires in series, 0.4575…+0.6+0.3=1.36 ohms which should be the right answer hopefully :smile:

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