The following table gives the length of three copper rods, their diameters, and the potential differences between their ends. Rank the rods according to (a) the magnitude of the electric field within them, (b) the current density within them, and (c ) the drift speed of electrons through them, greates first.

Explanation

a. `E_1= (V)/(L), E_2 = (2)/(2L) = (V)/(L), E_3 = (2V)/(3L)`.
Hecne, `E_1 =E_2 gt E_3`
c. `V_d prop E`. Hence, `V_(d_1) = V_(d_2) gtV_(d_3)`
b. `I = "ne"Av_d = (nepid^2)/(4) = v_d = (mepi)/(4)v_dd^2`
or `I prop v_dd^2 or I prop Ed^2 or I = Ked^2`
`I_1= (KV)/(L)(3d)^2 = (9Kvd^2)/(L), I_2 = K(V)/(L)d^2A`
`I_3 = K(2V)/(3L)(2d)^2 = (8KV d^2)/(3L)`
Hence,`I_1gt I_3gtI_2.`