Physics help (i) A magnetic field B = 0. 22 Tesla causes the beam to go into a c
ID: 2288391 • Letter: P
Question
Physics help (i) A magnetic field B = 0. 22 Tesla causes the beam to go into a curved-path of radius Rand the beam is deflected making a fluorescent spot in the upper- half of the glass f flask screen. When a potential difference V = 4000 Volts IS applied across the plates with separation d= 4 cm, the beam deflection vanishes. The spot falls straight at the center of the screen. Find the speed of electrons beam. (ii) Knowing the charge and mass of electrons, e=1.6x10^-19 C and 9.11 x 10^-31 kg, respectively, calculate the radius R of the curved-path of the beam when V = 0? Hint: The Lorentz Force, Fq = q E + q uxB and Newton?s Law F ma, EV/d and acp = mu^2/RExplanation / Answer
i) Fnet = 0
Elelctric force - magnetic force = 0
q*E - q*u*B = 0
u = E/B
= V/(d*B)
= 4000/(0.04*0.002)
= 5*10^7 m/s
ii) Apply, m*v^2/r = q*v*B
r = m*v/(B*q)
= 9.1*10^-31*5*10^7/(0.002*1.6*10^-19)
= 0.142 m