Question

Inkjet printers can be described as either continuous or drop-on-demand. In a continuous inkjet printer, letters are built up by squirting drops of ink at the paper from a rapidly moving nozzle You are part of an engineering group working on the design of such a printer. Each ink drop will have a mass of 1.6x10-8 g. The drops will leave the nozzle and travel toward the paper at 50 m/s, passing through a charging unit that gives each drop a positive charge q by removing some electrons from it. The drops will then pass between parallel deflecting plates, 2 cm long, where there is a uniform vertical electric field with magnitude 6.0 104 N/C. Your team is working on the desigrn of the charging unit that places the charge on the drops If a drop is to be deflected 0.40 mm by the time it reaches the end of the deflection plates what magnitude of charge must be given to the drop? Express your answer with the appropriate units qValue Units Submit Previous Answers Request Answer

Answer 1

Solution:-

Given data:-

d=0.00040, m =1.6*10^-11kg,

E=8.0*10^4 N/C, y=0.02m,

v= 50m/s

Applying Newton’s 2^nd law to the drop,

Fnet = ma

qE=ma

a=qE/m -------------(1)

By kinematic equation,

d=1/2at^2 -------------(2)

Put (1) in (2),

d=1/2*qE/m*t^2

Simplifying for ‘q’

q=2dm/Et^2---------------(3)

t=y/v ---------------(4)

Put (4) in (3)

q=2dm/[E(y/v)^2] -----------------(5)

q=(2*0.00035*1.6*10^-11)/(8.0*10^4*(0.02/50)^2)

= 1*10^-12C