Ahollow aluminum cylinder is 2.50 m long and has an inner radius of 2.75 cm and an outer radius of 4.60 cm. treat each surface (inner, outer, and the two end faces) as an equipotential surface. at room temperature, what will an ohmmeter read if it is connected between (a) the opposite faces and (b) the inner and outer surfaces?

a)  1.609× 10⁻⁵ Ω

b) 9 × 10⁻¹⁰ Ω

Explanation:

length of cylinder = 2.50 m

inner diameter  =  2.75 cm

outer diameter = 4.60 cm

as we know,

a) resistance of cylinder across the length

area of cylinder =

                          =

                          = 42.71 × 10⁻⁴ m²

         =  1.609× 10⁻⁵ Ω

b) reading of inner and outer surface in ohmmeter means

assume r is radius of the cylinder and dr be thickness

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask