TEST SET 1 Basic Principles of ElectricityProblem 1: Past EE Board ExamThe substation bus bar is made up of 2-inches round copper bars 20 ft. long. What is the resistance of each bar if resistivity is 1.724 x 10-6 ohm-cm.A. 7.21 x 10-5 ohmB. 13.8 x 10-6 ohmC. 5.185 x 10-5 ohmD. 2.96 x 10-5 ohm

Problem 2: Past EE Board ExamDetermine the resistance of a bus bar made of copper if the length is 10 meters long and the cross-section is a 4 x 4 cm2. Use 1.7241 micro ohm-cm as the resistivity.

A. 2.121 x 10-4 ohmB. 4.312 x 10-4 ohmC. 3.431 x 10-5 ohmD. 1.078 x 10-4 ohm

Problem 3: Past EE Board ExamOne turn of a copper bar is produced by cutting a copper washer along a radius and spreading the ends. The washer is cut from soft-drawn copper having a resistivity at 20C of 1.732 x 10-6 ohm-cm. The washer is 0.125 inch thick and has inside diameter and outside diameter of 1 inch and 9 inches respectively. Calculate the exact resistance between the two ends of the turn to direct current, taking into account the non-uniform current distribution. Assume the contact along the ends of the turn to be perfect over the entire cross-section.

A. 12.74 x 10-6 ohmB. 15.53 x 10-6 ohmC. 17.22 x 10-6 ohmD. 14.83 x 10-6 ohm

Problem 4: Past EE Board ExamDetermine the resistance of a conductor 0.10m long, with a uniform diameter of 1.0cm and having a resistivity which varies as a function of length L measured from one end of the conductor according to the formula: p = 0.003 + 10-4 L2 ohm-cm.

A. 0.0852 ohmB. 0.0915 ohmC. 0.0806 ohmD. 0.0902 ohm

Problem 5: Past EE Board ExamA coil has 6,000 turns of wire and a resistance of 380 ohms. The coil is rewound with the same quantity (weight) of wire, but has 13,400 turns. How many ohms will the new coil have?

A. 1895 ohmsB. 1825 ohmsC. 1792 ohmsD. 1905 ohms

Problem 6: Past EE Board ExamA copper wire of unknown length has a resistance of 0.80 ohm. By successive passes through drawing dies, the length of the wire is increased to 2 times its original value. Assuming that resistivity remains unchanged during the drawing process, determine the new value of its resistance.

A. 4B. 3C. 5D. 6

Problem 7: Past EE Board ExamA one-meter rod of 2-cm diameter is drawn until its resistance is 100 times the initial resistance. Its length afterward is?

A. 10 mB. 100 mC. 12.5 mD. 5 m

Problem 8: Past EE Board ExamA kilometer of wire having a diameter of 11.7 mm and a resistance of 0.031 ohm is drawn down so that its diameter is 5.0 mm. What does its resistance become?

A. 0.85 ohmB. 0.78 ohmC. 0.93 ohmD. 0.81 ohm

Problem 9: Past EE Board ExamA certain wire has a resistance R. The resistance of another wire identical with the first except for having twice its diameter is

A. 4RB. RC. 2RD. R

Problem 10: Past EE Board ExamWhat is the size in square millimeter (mm2) is the cable of 250 MCM size?

A. 118.656 mm2B. 126.675 mm2C. 112.565 mm2D. 132.348 mm2

Problem 11: Past EE Board ExamThe resistance of a copper wire at 30C is 50 ohms. If the temperature coefficient of a copper at 0C is 0.00427, what is the resistance at 100C?

A. 72.26 ohmsB. 54.25 ohmsC. 63.24 ohmsD. 58.15 ohms

Problem 12: Past EE Board ExamThe resistance of a wire is 126.48 ohms at 100C and 100 ohms at 30C. Determine the temperature coefficient of copper at 0C.

A. 0.00427B. 0.00615C. 0.0256D. 0.0356

Problem 13: Past EE Board ExamTwo heating elements which is 500 ohms and 250 ohms are connected in series with temperature coefficients of 0.001 and 0.003 ohms per C, respectively at 20C. Calculate the effective temperature coefficient of the combination.

A. 0.00215B. 0.00626C. 0.00712D. 0.00167

Problem 14: Past EE Board ExamThe insulation resistance of a kilometer of the cable having a diameter of 2 cm and an insulation thickness of 2 cm is 600 ohms. If the thickness of the insulation is increased to 3 cm, find the insulation resistance of the cable.

A. 725 ohmsB. 850 ohmsC. 757 ohmsD. 828 ohms

Problem 15: Past EE Board ExamThe resistance of n120 meters of wire is 12 ohms. What is its conductance?

A. 0.0521 mhoB. 0.083 mhoC. 6 mhosD. 12 mhos