3. According to Gauss theorem ∫Eds=Q/ε0 and spherical symmetry, we can calculate:

0 & ltr & lt=R 1 E=0

r 1 & lt； r & lt= R2 E = q 1/(4ω0r？ )

R2<r E =(q 1+Q2)/(4ω0r？ )

4、

0<r< is in the range of =R 1, and the amount charged is Q 1r? /R 1？ Then E=Q 1r? /(R 1？ (4ω0r？ ))= q 1r/(4ω0r 1？ )

r 1 & lt； r & lt= R2 E = q 1/(4ω0r？ )

R2<r E =(q 1+Q2)/(4ω0r？ )

The potential can be obtained by integrating the field strength with r in segments at infinity:

R2<r U =(q 1+Q2)/(4ω0r)

r 1 & lt； r & lt= R2 U =(q 1+Q2)/(4ω0r 2)+q 1/(4ω0)( 1/r- 1/R2)= q 1/(4ω0r)+Q2/(4ω0r 2)

0 & ltr & lt= r 1 U =(3q 1/(2r 1)+Q2/R2)/(4ω0)-q 1 r？ /(8ω0r 1？ )