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
Figure P27.49
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Chapter 27 Solutions
PHYSICS:F/SCI.+ENGRS-W/WEBASSIGN
- 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?arrow_forward1.00 MQ A conducting sphere is charged by an emf source E through a 1.00 MO resistor. When the sphere is fully charged, it has 2 µC charge. The highest current during the charging was I mA. What is the electrical potential energy of the sphere when it is fully charged? Give your answer in mJ.arrow_forwardMaterial with uniform resistivity p is formed into a wedge as shown in Figure P26.50. Show that the resistance between face A and face B of this wedge is L R= p In w(y2 – y,) Face A Face B Figure P26.50arrow_forward
- Two conductors are made of the same material and have the same length. Conductor A is a solid wire of diameter 1.1 mm. Conductor B is a hollow tube of outside diameter 2.5 mm and inside diameter 1.4 mm. What is the resistance ratio RA/RB., measured between their ends? Number Unitsarrow_forwarda.Estimate the electrical resistance of the blood in a 50cm long, 3mm diameter artery. The resistivity of blood is 1.6 ohm-meter.Express your answer in cΩ, mΩ,μΩ, and nΩ. B. Suppose the energy for two doughnuts in Thermodynamics are totally converted into electric potential energy at point a, wherein a dust particle of 5 × 10-9 kg with 9nC charge is travelling from point a with 600 m/s to point b (where there is no electric potential energy). How fast does the dust particle is moving at point b?arrow_forwardA cell membrane has a resistance and a capacitance and thus a characteristic time constant. What is the time constant of a 9.0-nm-thick membrane surrounding a 0.040-mm-diameter spherical cell?arrow_forward
- 1.00 MQ A conducting sphere is charged by an emf source E through a 1.00 MQ resistor. When the sphere is fully charged, it has 1 µC charge. The highest current during the charging was 1 mA. What is the radius of the sphere in meters?arrow_forwardYou are working with an oceanographer who is studying how the ion concentration in seawater depends on depth. She shows you the device that she uses to measure the resistivity of water from a boat. It consists of a pair of concentric metallic cylinders at the end of a cable (as shown). Seawater flows freely between the two cylindrical shells. She makes a measurement by lowering the device into the water and applying a potential difference ΔV between the inner and outer cylinders. This produces an outward radial current I in the seawater between the shells. She shows you the current and voltage data for the water at a particular depth and is then called away to answer a long call on her cellphone about a laboratory issue back on the mainland. As she leaves, she says, “Have the resistivity of the water calculated when I get back.” She forgot to show you any tables or formulas to use to determine the resistivity, so you are on your own. Quick! Find an expression for the resistivity in…arrow_forwardWhat is the time constant of the circuit shown in Figure OQ28.7? Each of the five resistors has resistance R. and each of the five capacitors has capacitance C. The internal resistance of the battery is negligible. (a) RC. (b) 5RC. (c) 10RC (d) 25RC (e) none of those answersarrow_forward
- If you touch the two terminals of a power supply with your two fingertips on opposite hands, the potential difference will produce a current through your torso. The maximum safe current is approximately 5 mA.a. If your hands are completely dry, the resistance of your body from fingertip to fingertip is approximately 500 kΩ. If you accidentally touch both terminals of your 120 V household electricity supply with dry fingers, will you receive a dangerous shock?b. If your hands are moist, your resistance drops to approximately 1 kΩ. If you accidentally touch both terminals of your 120 V household supply with moist fingers, will you receive a dangerous shock?arrow_forwardA 60 W lightbulb has a resistance of 240 Ω. At the operating temperature of the tungsten filament, its resistivity is approximately 5.0 x 10-7 Ω • m. If the wire used to make the filament is 0.040 mm in diameter (a typical value). As described above the length of a 60 W, 240 Ω lightbulb filament was calculated to be 60 cm.a. If the potential difference across the filament is 120 V, what is the strength of the electric field inside the filament?b. Suppose the length of the bulb’s filament were doubled without changing its diameter or the potential difference across it. What would the electric field strength be in this case?c. Remembering that the current in the filament is proportional to the electric field, what is the current in the filament following the doubling of its length?d. What is the resistance of the filament following the doubling of its length?arrow_forwardHigh-resolution measurements have shown that an ion channel (see the attached problem) is a 0.30-nm-diameter cylinder with length of 5.0 nm. The intracellular fluid filling the ion channel has resistivity 0.60 Ω • m. What is the resistance of the ion channel?arrow_forward