electric field due to surface and volume charge distributions

Question 1

Electric field strength due to uniformly surface charged disc

Answer 1

σ[1- 1/√(x² + R²)]/2⋲o

σ is surface charge density C/m^2
⋲o- permittivity of free space

Question 2

lectric field due to uniformly charged sheet (infinitely large)

Answer 2

σ/2⋲o

Question 3

electric field strength in vicinity of centre of uniformly charged disc

vicinity means near the surface

Answer 3

σ/2⋲o

Question 4

E. field due to uniformly charged hollow hemispherical cup

Answer 4

σ/4⋲o