100 PROBLEMS IN ELECTRICAL ENGINEERING PART – 07 – PROBLEMS ON RESISTANCE AND RESISTIVITY

PROBLEM – 01

Find the resistance of the aluminum conductor shown in figure. The length of conductor is 2 m and resistivity = 2.83 x 10^-5.

PROBLEM – 02

A liquid resistor consists of two metallic tubes radii R and r respectively. Each tube has length l. The space between tubes is filled sea water having resistivity of 0.2 ohm-metre. Find the resistance if R = 20 cm and r = 10 cm and l = 2m.

PROBLEM – 03

Find the resistance of aluminum tube of external diametre D, internal diametre d, length l and resistivity is 2.83 x 10^-8. If D = 20 cm, l = 6 cm and thickness of the tube is 1.5 cm. Find the resistance of the tube.

PROBLEM – 04

A liquid resistance has paralleled plate electrode. It is rated 50 kW, 220 V, d.c. supply. The liquid has resistivity of 0.5 ohm-metre. Find the distance between the plates if current density at electrode is 0.5 amps per square centimetre.

PROBLEM – 05

A resistor has cylindrical shape with radius r1 and length l1. It is recast with a triangular cross section (right angle triangle with sides r2) and appropriate length l2. Find its second resistance R2 in terms of first R1.