a) An electric field of 436 N/C passes through an area of 3.9 cm 2 . Calculate t

Question

a) An electric field of 436 N/C passes through an area of 3.9 cm2. Calculate the flux in N.m2/C, to 2 sf. You can assume that the electric field is perpendicular to the surface.

b) A volume of space has a net flux of 4099.5 N.m2/C INTO the volume. Calculate the charge inside the volume , in Coulombs to 2 sf.

c) When do equipotential surfaces and electric field lines cross?

Select one:

a.Always, at 90 degree angles to each other.

b. Never, they always run parallel to each other

c. It depends on the strength of the electric field

d) A dielectric is placed between the plates of a parallel plate capacitor. What happens to the capacitance?

Select one:

a. It will increase

b. It will decrease

c. It will stay the same

e)If you have a parallel plate capacitor, what will happen to the capacitance if you move the plates further apart

Select one:

a. It will increase

b. It will stay the same

c. It will decrease

Explanation / Answer

Given

a) electric field E = 436 N/C passes through area A = 3.9 cm2 = 3.9*10^-4 m2

   we know that the electric flux phi = E*A cos theta

                   = 436*3.9*10^-4 N m2/C
                   = 0.17 Nm2/C

b) electric flux phi = 4099.5 Nm2/C

   from Gauss law

   flux through a closed surface phi = (1/epsilon not)(charge inside)

                  
where epsilon not is permitivity of free space = 8.85*10^-12 F/m

   so the charge inside is Q_in = 4099.5*8.85*10^-12

                   = 3.6280575*10^-8 C  
                   = 36.28 nC
      
c)

   in equipotential surface the electric field lines are always perpendicular to each other

answer is option
a.Always, at 90 degree angles to each other.

d) A dielectric is placed between the plates of a parallel plate capacitor

Ans the capacitance

a. It will increase

   C = k*C0
C0 is capacitance without dielectric material , k is dielectric material of constant k

e) ans C It will decrease

because when separation between plates increases , capacitance decreases

       C = epsilon not *A/d
   as d increases , C decreases

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