Câu 1: 

Ta có: 

\(E = \dfrac{{k\left| q \right|}}{{{r^2}}} = \dfrac{{{{9.10}^9}{{.4.10}^{ - 8}}}}{{0,{{06}^2}}} = {10^5}\left( {V/m} \right)\)

Câu 2: 

Ta có: 

\(F = \dfrac{{k\left| {{q_1}{q_2}} \right|}}{{{r^2}}} = \dfrac{{{{9.10}^9}{{.3.10}^{ - 8}}{{.2.10}^{ - 8}}}}{{0,{1^2}}} = 5,{4.10^{ - 4}}N\)

Câu 3: 

Ta có: 

\({A_{MN}} = q{U_{MN}} = {2.10^{ - 8}}.\left( { - 60} \right) =  - 1,{2.10^{ - 6}}J\)

Câu 4: 

a) Ta có: 

\({U_{BC}} = E.BC = {6.10^4}.0,05 = 3000V\)

b) Ta có: 

\(A = q{U_{CB}} =  - 1,{6.10^{ - 19}}.\left( { - 3000} \right) = 4,{8.10^{ - 16}}J\)