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1) A beam of protons is accelerated easterly from rest through a potential diffe

ID: 1282942 • Letter: 1

Question

1) A beam of protons is accelerated easterly from rest through a potential difference of 2.0kV. It enters a region where there exists an upward pointing uniform electric field. This field is created by two parallel plates separated by 18cm with a potential difference of 250V across them.

Find the magnitude of the magnetic field (perpendicular to E) needed so the beam passes undeflected through the plate. B = --------------- T

2) Two long, parallel wires separated by 50cm each carry currents of 2.0A in a horizontal direction.

Find if they are in opposite directions. B = ----------------- T

Explanation / Answer


1. eLECTRIC FIELD E = V/d

E = 250/0.18

E = 1.388*10^3 N/C

as E = BV

speed v =    sqrt(2eV/m)

v = sqrt(2*1.6e-19 * 2000/9.11e-31)

v = 2.65*10^7 m/s


B = 1.388e3/(2.65e7)

B = 5.23*10^-5 T

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Bnet = B1- B2

Bnet = 0