In a cathode-ray tube CRT an electron traves in a vacuum and enters a region bet
ID: 1771435 • Letter: I
Question
In a cathode-ray tube CRT an electron traves in a vacuum and enters a region between two deflection plates which have equal and opposite charges. The dimensions o each plate are L-13 cm by d = 5 cm and the gap between them IS h = 2.5 mm. (Note: the diagram not drawn to scale and the direction of the electric field may not be correct, depending on your randomization.) -1 During a o.001 s interval while it is between the plates, the change of the momentum of the electron Ap is kg m/s. What is the electric field between the plates? Hint: remember the Momentum Principle (the relationship between Impse and change in momentum.) What is the charge (both magnitude and sign) of the upper plate? Additional Materials Section 15.6Explanation / Answer
Given,
L = 13 cm ; d = 5 cm ; h = 2.5 cm
t = 0.001 s ; p = <0,7.2 x 10^-17,0>
We know that the change in momentum is :
delta-p = F t
F here is ; q E
delta-p = q E t
E = delta-p/q t
E = 7.02 x 10^-17/(1.6 x 10^-19) x 0.001 = 438750 N/C
Hence, E = 4.3875 x 10^5 N/C
We know that,
E = Q/A e0 = Q/L d e0
Q = E L d e0
Q = 4.3875 x 10^5 x 0.13 x 0.05 x 8.85 x 10^-12 = 2.524 x 10^-8 C
Hence, Q = 2.524 x 10^-8 C