. A source of constant potential difference is connected across a conductor having irregular cross section as shown. Then
a. electric field intensity at P is greater than that at Q
b. rate of electrons crossing per unit area of cross-section at P is less than that at Q
c. the rate of generation of heat per unit length at P is greater than at Q
d. mean kinetic energy of free electrons at P is greater than that at Q
Sol: When a source is connected, a current starts to flow through the conductor. Let it be I. Then, current density at a section is equal to I/A, where A = cross-sectional area.
Since cross-sectional area at P is maximum, therefore current density at P is minimum