2. The polar molecule in the diagram below has a positive charge of +19e at one

Question

2. The polar molecule in the diagram below has a positive charge of +19e at one end and a negative charge of -19e at the other. It is immersed in a non- uniform electric field (and aligned with the field direction). The magnitude of the field is 4.6 x 107 N/C at the negative end of the molecule and drops by 3% at the positive end. a) Determine the net force that acts on the molecule (calculate the magnitude and describe the direction). b) What would the net force on the molecule be if the field were uniform with a constant magnitude of 4.6 x 107 N/C? c) Water is a polar molecule. Imagine a stream of water falling through a region of space where an electric field exists. How could this experiment be used to determine if the electric field is uniform or non uniform? Explain your reasoning and describe how you could use your observations to reach a conclusion.

Explanation / Answer

a)
E- = 4.6*10^7 N/C
F- = q*E-
= (-19*1.6*10^-19)*(4.6*10^7)
= -1.398*10^-10 N

E+ = 4.6*10^7 - 3% of 4.6*10^7
= 4.6*10^7 - 0.03 * 4.6*10^7
= 4.462*10^7 N/C

F+ = q*E+
= (19*1.6*10^-19)*(4.462*10^7)
= 1.356*10^-10 N

net force = |F+ + F-|
= | 1.356*10^-10 -1.398*10^-10 |
= 4.2*10^-12 N/C

b)
Since Eon positive chnarge is equal to E on negative force
Force on both will be equal in magnitude but opposite in direction/
So Net force = 0 N

c)
Water is falling
If Electric field is uniform, it will keep falling without deviation since net force acting on nit will be 0
But if Electric field is non uniform, it will deviate from its apth as net force will not be zero in this case

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