You know that Wires 1 and 2 are a distance, d = 0.81 m, apart and that they carry the same current, I = 18.7 A, in opposite directions. You also know that Wires 2 and 3 are a distance, x = 2.43 m, apart. What you don't know, but really need to find out, is ... "How much current flows through Wire 3 -- and which way?" You would just measure the current, if your ammeter wasn't broken. Then you remembered the magnetometer that the Tooth Fairy left under your pillow last year, and realized that you could deduce the current in Wire 3 from the measured magnetic field strength! (b) Calculate the magnetic force per unit length that acts on the new wire. FB on 3 L N/m = (c) Will Wire #3 be attracted or repelled by the other two? O attract out (a) Using the magnetometer, you determined that the magnetic field midway between Wires 2 and 3 was 2.9 μT, and that it pointed straight upwards. What then is the size and direction of the current flowing through wire 3? 13 = A and it flows --Select--- repel I right down wire 1 wire 2 wire 3

Taking R = 1.20 kΩ and ℰ = 470 V in the figure shown below, determine the magnitude and direction of the current in the horizontal wire between a and e. magnitude ?mA

Taking R = 1.50 kΩ and ε = 150 V in the figure shown below, determine the magnitude and direction of the current in the horizontal wire between a and e. 17.5 mA, from e to a19.9 mA, from a to e    18.0 mA, from e to a18.9 mA, from a to e18.0 mA, from a to e19.9 mA, from e to a

A 60.5 m length of insulated copper wire is wound to form a solenoid of radius 2.2 cm. The copper wire has a radius of 0.51 mm. (Assume the resistivity of copper is p = 1.7 x 10-8. m.) (a) What is the resistance of the wire? Ω (b) Treating each turn of the solenoid as a circle, how many turns can be made with the wire? turns (c) How long is the resulting solenoid? m (d) What is the self-inductance of the solenoid? mH (e) If the solenoid is attached to a battery with an emf of 6.0 V and internal resistance of 350 m2, compute the time constant of the circuit. ms (f) What is the maximum current attained? A (g) How long would it take to reach 99.9% of its maximum current? ms (h) What maximum energy is stored in the inductor? mJ

In the accompanying figure, the rails, connecting end pieces, and rod all have a resistance per unit length of 40/cm. The rod moves to the left at v = 3 m/s. If B = 0.65 T everywhere in the region, what is the current in the circuit (a) when a = 8 cm? (b) when a = 4.5 cm? Description of Image B Hint a. When a = 8 cm, a counterclockwise mA flows in the circuit. b. When a = = 4.5 cm, 5.48 o current of 9.75 4.0 cm X = 5.48 mA flows in the circuit. X = 9.75

Ch. 26

Lets say the following electric currents flow into a junction of wires: 6.6 A (amperes or amps), -2.2 A, 6.7 A,  and last but not necessarily least 9.2 A.   What current in A flows out of that very busy junction?

A caterpillar of length 6.00 cm crawls in the direction of electron drift along a 8.20-mm-diameter bare copper wire that carries a uniform current of 38.0 A. (a) What is the potential difference between the two ends of the caterpillar? (b) Is its tail positive or negative relative to its head? (c) How much time does the caterpillar take to crawl 2.30 cm if it crawls at the drift speed of the electrons in the wire? (The number of charge carriers per unit volume is 8.49 × 1028 m-3 and resistivity of copper is 1.69 × 10-8 Ω·m.)