Section2 You observe an electron moving on your test paper in a clockwise circle
ID: 1787417 • Letter: S
Question
Section2 You observe an electron moving on your test paper in a clockwise circle of radius H. 10.0 cm, at a constant speed ofI. 5.6x 106 m/s (a) Suppose that the electron's circular motion is due to the presence of a uniform magnetic field. What must be the magnitude and direction of this magnetic field? Answer: x 10 T (for the magnitude) Answer for direction: choose from the following six possibilities and circle the correct one Toward the top of the page To the left Toward you Toward the bottom of the page To the Right Away from you (b) Suppose instead that the electron's circular motion is due to the presence of a stationary charged particle located at the center of the circle. What is the value of this stationary charge? Make sure to specify the correct sign on the charge in your answer. Answer: x 10 CExplanation / Answer
(a)
In the uniform magentic field magnetic force proivdes necessary centripetal force
Fb = Fc
q*v*B = m*v^2/R
B = m*v/(R*q)
m = mass of electron = 9.1*10^-31 kg
R = raidius = 10 cm = 0.1 m
v = speed = 1.5*10^6 m/s
q= cahrge of electron = 1.6*10^-19 C
B = 9.1*10^-31*1.56*10^6/(0.1*1.6*10^-19)
B = 8.875*10^-5 T
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direction = away from you
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the electrostatic force of attraction provides necessary centripetal force
Fe = Fc
k*q*e/r^2 = m*v^2/r
e = charge of electron
q = m*v^2*r/(k*e)
q = 9.1*10^-31*(1.56*10^6)^2*0.1/(9*10^9*1.6*10^-19)
charge of particle q = +1.54*10^-9 C <<<<------------ANSWER