Question

Physics question help. Answer these 4 questions with correct units: What is the strength of the electric field 4.4 cm from a small plastic bead that has been charged to -8.6 nC ? What is the strength of the electric field Ee 0.60 mm from an electron?

Answer 1

given,

r = 4.4 cm = 0.044 m ; Q = -8.6 nC = 8.6 x 10^-9 C

we know that

E = k q/r

E = 9 x 10^9 x 8.6 x 10^-9/0.044^2 = 3.99 x 10^4 N/C

Hence, E = 3.99 x 10^4 N/C

Now, r = 0.6 mm = 0.6 x 10^-3 m

Again using the same formula

E = 9 x 10^9 x 1.6 x 10^-19/(0.6 x 10^-3)^2 = 4 x 10^-3 N/C

Hence, E = 4 x 10^-3 N/C