Q18 and 19
18. Two large conducting plates are placed parallel to each
other with a separation of 2 cm between them. An electron
starting from rest near one of the plates reaches the other
plate in 2 . Find the surface charge density of the plate.
[Ans. 2-52 x 10-13 Cm-2]
19. In problem no. 17, if the two conducting plates are replaced
by two sheets of charge ,what will be the charge density of
the sheets of charge ?
[Ans. 5.04 x 10-13 Cm-2]
Dear Student ,
Mass of the electron: m = 9.1 x 10 -31 kg
Charge of the electron: e= -1.6 x 10 -19 C
Permittivity of vacuum: ε₀ =8.854 x 10 -12 F/m
d=0.02 m
t=2 x 10-6 s
We know that , F=ma
Again from electrostat we can write that , F=eE
Now ,
E = σ/ε₀
Therefore , F = eσ/ε₀
So , d=at2/2
or , a=2d/t2
Therefore , eσ/ε₀=2dm/t2
or , σ = 2dmε₀ /et^2 [C/m2]
Now by putting the values we get ,
σ = 5.03 x 10-13 C/m2
Kindly ask different question in different posts .
Regards
Mass of the electron: m = 9.1 x 10 -31 kg
Charge of the electron: e= -1.6 x 10 -19 C
Permittivity of vacuum: ε₀ =8.854 x 10 -12 F/m
d=0.02 m
t=2 x 10-6 s
We know that , F=ma
Again from electrostat we can write that , F=eE
Now ,
E = σ/ε₀
Therefore , F = eσ/ε₀
So , d=at2/2
or , a=2d/t2
Therefore , eσ/ε₀=2dm/t2
or , σ = 2dmε₀ /et^2 [C/m2]
Now by putting the values we get ,
σ = 5.03 x 10-13 C/m2
Kindly ask different question in different posts .
Regards