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At what angle will the electrons in Example 21-16 (Giancoli Physics for Engineer

ID: 1686598 • Letter: A

Question

At what angle will the electrons in Example 21-16 (Giancoli Physics for Engineers and Scientists 4th Ed.) leave the uniform electric field at the end of the parallel plates (point P in the figure)? Assume the plates are 6.4 cm long and E = 4.6 × 10^3 N/C. Ignore fringing of the field. At what angle will the electrons in Example 21-16 (Giancoli Physics for Engineers and Scientists 4th Ed.) leave the uniform electric field at the end of the parallel plates (point P in the figure)? Assume the plates are 6.4 cm long and E = 4.6 10^3 N/C. Ignore fringing of the field.

Explanation / Answer

when an electron enters the electric field it has velocity v in x- direction. the electron pointing vertically upward imparts a uniform acceleration to the electron                  a = F / m                        = - E q / m where q = charge on electron = 1.6*10^ -19 C              m = mass of electron = 9.11*10^ -31 kg              E  = electric field between between the plates = 4.6*10^ 3 N /C                    The electron vertical position                y = ( 1 /2 ) a t^2                    = ( 1 /2 ) (- Eq / m ) t^2   ........(1)               sin ce horizontal component of acceleration is constant .the horizonatl position is                x = v cos? t                t = x / v cos?     substitute t value in equation                  y =  [ - Eq / 2m (vcos?)^2 ] x^2        where y = distance between the plates               x = length of the plates         substitue the values and simplify the equation and get the angle.