A cylindrical capacitor is constructed using two coaxial cylinders of the same length 10 cm and of radii 2 mm and 4 mm.
a) Calculate the capacitance.
b) Another capacitor of the same length is constructed with cylinders of radii 4 mm and 8 mm. Calculate the capacitance.
Given
Length, l = 10cm
Radius, R1 = 2mm
Radius, R2 = 4mm
Formula used :
a) The capacitance of the cylindrical capacitor is given by
Where
l→ length of the cylinder
R2→ radius of outer cylinder
R1→ radius of inner cylinder permittivity of the free space
ε₀→ permittivity of the free space = ε₀=
Putting the value in the above formula, we get
b) Another cylindrical capacitor of same but different radius R1=4mm and R2= 8mm
If we compare the radii in a) with b), they give the same ratio
So capacitance is also same as a) is
Capacitance of cylindrical capacitor for both a) and b) is same and is =8pF