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Turn on your desk lamp. Pick up the cord, with your thumb and index finger spanning the width of the cord. (a) Compute an order-of-magnitude estimate for the current in your hand. Assume the conductor inside the lamp cord next to your thumb is at potential ~ 102 V at a typical instant and the conductor next to your index finger is at ground potential (0 V). The resistance of your hand depends strongly on the thickness and the moisture content of the outer layers of your skin. Assume the resistance of your hand between fingertip and thumb tip is ~ 104 Ω. You may model the cord as having rubber insulation. State the other quantities you measure or estimate and their values. Explain your reasoning. (b) Suppose your body is isolated from any other charges or currents. In order-of-magnitude terms, estimate the potential difference between your thumb where it contacts the cord and your finger where it touches the cord.
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Chapter 28 Solutions
Physics for Scientists and Engineers, Technology Update (No access codes included)
- A 0.900-V potential difference is maintained across a 1.50-m length of tungsten wire that has a cross-sectional area of 0.600 mm2. What is the current in the wire?arrow_forwardThe student engineer of a campus radio station wishes to verify the effectiveness of the lightning rod on the antenna mast (Fig. P21.71). 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 Earths 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 be Rx 2.00 . Is the grounding of the station adequate if measurements give R1 = 13.0 and R2 = 6.00 ? Explain. Figure P21.71arrow_forwardWhale and Kanmuro are two islands located in the Chimera archipelago. These two are separated by a distance of 20 miles. A power link is to be established between them. The power link delivers a maximum power of 600 MW at full capacity with an operating voltage of 500 kV. Solve for the resistivity of the cable, assuming a conductor diameter of 1.5 cm. Express your answer in uQ-m.arrow_forward
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- Please help: A typical cell membrane is 8.0 nm thick and has an electrical resistivity of 1.3 x 10^7 Ω•m (A) If the potential difference between the inner and outer surfaces of a cell membrane is 75 mV, how much current flows through a square area of membrane 1.0 micrometers on a side? Express your answer using two significant figures (B) Suppose the thickness of the membrane is doubled, but the resistivity and potential difference remain the same. Does the current increase?arrow_forwardA coaxial cable of consists of two concentric cylindrical conductors. The region between the conductors is completely filled with polyethylene plastic. The radius of the inner conductor is 0.50 cm, the radius of the outer conductor is 1.75 cm, and the length of the cable is 15 cm. The resistivity of the plastic is 1013 Ω • m. Calculate the resistance of the plastic if the electric field is applied across the ends of the conductor.arrow_forwardSuppose you have a rod of pure silicon with a diameter of 2.79cm and a length of 20.6cm. These rods are often used in experiments, such as the Large Hadron Collider in France/Switzerland to detect high-energy particles, and they have a very high resistivity of 2300Ω⋅m. What current, in amperes, flows through the rod when a potential difference of 1.23* 10^3 V is applied between its ends ?arrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning
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