The student engineer of a campus radio station wishes to verify the effectiveness of the lightning rod on the antenna mast (Fig. P27.49). The unknown resistance R x is between points C and E . Point E is a true ground, but it is inaccessible for direct measurement because this stratum is several meters below the Earth’s surface. Two identical rods are driven into the ground at A and B , introducing an unknown resistance R y . The procedure is as follows. Measure resistance R 1 between points A and B , then connect A and B with a heavy conducting wire and measure resistance R 2 between points A and C . (a) Derive an equation for R x in terms of the observable resistances, R 1 , and R 2 . (b) A satisfactory ground resistance would R x < 2.00 Ω. Is the grounding of the station adequate if measurements give R 1 = 13.0 Ω and R 2 = 6.00 Ω? Explain. Figure P27.49
The student engineer of a campus radio station wishes to verify the effectiveness of the lightning rod on the antenna mast (Fig. P27.49). The unknown resistance R x is between points C and E . Point E is a true ground, but it is inaccessible for direct measurement because this stratum is several meters below the Earth’s surface. Two identical rods are driven into the ground at A and B , introducing an unknown resistance R y . The procedure is as follows. Measure resistance R 1 between points A and B , then connect A and B with a heavy conducting wire and measure resistance R 2 between points A and C . (a) Derive an equation for R x in terms of the observable resistances, R 1 , and R 2 . (b) A satisfactory ground resistance would R x < 2.00 Ω. Is the grounding of the station adequate if measurements give R 1 = 13.0 Ω and R 2 = 6.00 Ω? Explain. Figure P27.49
Solution Summary: The author explains the equation for R_x in terms of the observable resistances.
The student engineer of a campus radio station wishes to verify the effectiveness of the lightning rod on the antenna mast (Fig. P27.49). The unknown resistance Rx is between points C and E. Point E is a true ground, but it is inaccessible for direct measurement because this stratum is several meters below the Earth’s surface. Two identical rods are driven into the ground at A and B, introducing an unknown resistance Ry. The procedure is as follows. Measure resistance R1 between points A and B, then connect A and B with a heavy conducting wire and measure resistance R2 between points A and C. (a) Derive an equation for Rx in terms of the observable resistances, R1, and R2. (b) A satisfactory ground resistance would Rx < 2.00 Ω. Is the grounding of the station adequate if measurements give R1 = 13.0 Ω and R2 = 6.00 Ω? Explain.
For the purpose of measuring the electric resistance of shoes
through the body of the wearer standing on a metal ground
plate, the American National Standards Institute (ANSI)
specifies the circuit shown in Figure P27.14. The potential
difference AVacross the 1.00-M2 resistor is measured with an
ideal voltmeter. (a) Show that the resistance of the footwear is
50.0 V – AV
shoes
AV
(b) In a medical test, a current through the human body
should not exceed 150 µA. Can the current delivered by the
ANSI-specified circuit exceed 150 µA? To decide, consider a
person standing barefoot on the ground plate.
1.00 MN
V
50.0 V
Figure P27.14
The following table gives the electric potential difference VT across the terminals of a battery as a function of current i being drawn from the battery. (a) Write an equation that represents the relationship between VT and i. Enter the data into your graphing calculator and perform a linear regression fit of VT versus i. From the parameters of the fit, find (b) the battery’s emf and (c) its internal resistance. i(A): 50.0 75.0 100 125 150 175 200 VT(V): 10.7 9.00 7.70 6.00 4.80 3.00 1.70
Two conductors are made of the same material and have the same length. Conductor A is a solid wire of diameter 1.0 mm. Conductor B is a hollow tube of outside diameter 2.0 mm and inside diameter 1.0 mm. What is the resistance ratio RA/RB, measured between their ends?
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DC Series circuits explained - The basics working principle; Author: The Engineering Mindset;https://www.youtube.com/watch?v=VV6tZ3Aqfuc;License: Standard YouTube License, CC-BY