Concept explainers
BIO Stray voltage is a serious problem on dairy farms, often resulting from corroded wiring or poor wiring practices. These conditions can produce several volts between the ground and metal watering bowls, feed troughs, or milking equipment. Cows feel shocks that make them nervous, reducing milk output and sometimes leading to mammary gland infections. As a result, farmers can face serious financial losses. Figure 25.43 shows a typical stray-voltage situation, with the source of stray voltage modeled as a 6-V emf in series with a 1-kΩ resistance.
FIGURE 25.43 Stray voltage can bankrupt a dairy farm (Passage Problems 83-86)
83. The current through the 500-Ω cow will be
- a. 3 mA.
- b. 4 mA.
- c. 6 mA.
- d. 12 mA.
84. The voltage across the cow shown is
- a. 2 V.
- b. 4 V.
- c. 6 V.
- d. nearly 0 V.
85. In an effort to diagnose the problem, a farmer connects an ideal voltmeter between the water bowl and ground, with the cow absent. The voltmeter reading is
- a. 2 V.
- b. 4 V.
- c. 6 V.
- d. none of the above.
86. To explore the problem further, a farmer connects an ideal ammeter between the water bowl and ground, with the cow absent. The ammeter reading is
- a. 4 mA.
- b. 6 mA.
- c. 12 mA.
- d. infinite.
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