Question

E-kg/ Possibly useful equations: Electric force: F kqyr Force from E field: F gE Electric potential: - kg/r PE-V Mag Fld near wire: B - .I/2 FqBsine k=9x10" Nm2/C2 = 4x x 10-7 N/A 1) A. What is the electric potential 2.5x10 m away from a proton (e-1.6x10°C)? B. A helium nucleus contains two protons, with typical separation of 2.5x10m. What is the electric potential energy due to the two protons? 2) A bare helium nucleus (2 protons, 2 neutrons, no electrons, -He") travels in the direction shown. In case i, on the left, the He nucleus is equidistant from two unknown plus charges. In case ii, on the right, the ion is equidistant from two neutral, current-carrying wires (current out of the page, as shown). О не A) Determine the direction of the instantaneous) net force on the He ion for each case above. Show your work so it is clear how you arrive at your final force vector. Also be certain it is clear which of your vectors is the net force, if you draw more than one vector, B) Suppose the He nucleus is replaced with a neutral helium atom (no net charge) as above. Which of the net force vectors would change and why? Draw new net force vectors on the helium atoms. 1) © C) Suppose we replace the He ion with a free electron. Further, suppose this electron travels directly upwards. Draw new net force vectors for the electron in both images. Explain how you arrived at your answer

Answer 1

"A electric potential va ka = 97 10² x 1-6x1019 2.571015 PE B 25.76*105 holt electic potential energy = Vq PE = 5.76+105 106x1019 = 9.22x1014 J Fret Frete - +*5)cose Ę Sino and a Fisino + - Bi q A B₂ B, coso Vebrical Components -- -- Bien-EE ) Cose Ę Sino ger Cancelled F= F₂ F = F as randa Hence Net force along are equal Horizontal direction away from Charges. (B, TB. ) Sino = Bower B, & B₂ are magnitic fields due to conductors O & ® respectively: B, =B as currents Hence net magnetic field is along verrical. (Horizontal components are equal & opposite) velocity is in plane of paper, Hence Force F = q (u xB) Hence it acts out of the paper and perpendicular to paper For He atom, wer charge =0 Hence in both the cases Free for electron 0 6 cose 0 and distance are equal B) - c)

Brer ---- ē facer: 0 field, Hence velocity parallel to magnetic Ewet=0