Physics for Scientists and Engineers
10th Edition
ISBN: 9781337553278
Author: Raymond A. Serway, John W. Jewett
Publisher: Cengage Learning
expand_more
expand_more
format_list_bulleted
Videos
Textbook Question
Chapter 27, Problem 31P
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.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
A straight, cylindrical wire lying along the x axis has a length L and a diameter d. It is made of a material described by Ohm’s law with a resistivity ρ. Assume potential V is maintained at the left end of the wire at x = 0. Also assume the potential is zero at x = L. In terms of L, d, V, ρ, and physical constants, derive expressions for (a) the magnitude and direction of the electric field in the wire, (b) the resistance of the wire, (c) the magnitude and direction of the electric current in the wire, and (d) the current density in the wire. (e) Show that E = ρJ.
Three wires, of the same diameter, are connected in turn between two points maintained at a constant potential difference. Their resistivities and lengths are r and L (wire A), 1.2r and 1.2L (wire B), and 0.9r and L (wire C). Rank the wires according to the rate at which energy is transferred to thermal energy within them, greatest first.
A straight, cylindrical wire lying along the x axis has a length of 0.5 m and a diameter of0.2 mm. It is made of a material described by Ohm’s law with a resistivity of ρ 4 × 10-8Ωm. Assume a potential of 4 V is maintained at the left end of the wire at x = 0. Alsoassume V = 0 at x = 0.5 m. Find (a) the magnitude and direction of the electric field in thewire, (b) the resistance of the wire, (c) the magnitude and direction of the electric currentin the wire, and (d) the current density in the wire. (e) Show that E = ρ J. (E = −dVdx)
Chapter 27 Solutions
Physics for Scientists and Engineers
Ch. 27.1 - To maximize the percentage of the power from the...Ch. 27.2 - With the switch in the circuit of Figure 27.4a...Ch. 27.2 - With the switch in the circuit of Figure 27.6a...Ch. 27.2 - Prob. 27.4QQCh. 27.4 - Consider the circuit in Figure 27.17 and assume...Ch. 27 - Two 1.50-V batterieswith their positive terminals...Ch. 27 - As in Example 27.2, consider a power supply with...Ch. 27 - Figure P27.3 shows the interior of a three-way...Ch. 27 - Prob. 4PCh. 27 - Consider the two circuits shown in Figure P27.5 in...
Ch. 27 - Consider strings of incandescent lights that are...Ch. 27 - You are working at an electronics fabrication...Ch. 27 - In your new job at an engineering company, your...Ch. 27 - A battery with = 6.00 V and no internal...Ch. 27 - A battery with emf and no internal resistance...Ch. 27 - Todays class on current and resistance is about to...Ch. 27 - Why is the following situation impossible? A...Ch. 27 - Calculate the power delivered to each resistor in...Ch. 27 - For the purpose of measuring the electric...Ch. 27 - Four resistors are connected to a battery as shown...Ch. 27 - You have a faculty position at a community college...Ch. 27 - The circuit shown in Figure P27.17 is connected...Ch. 27 - The following equations describe an electric...Ch. 27 - Taking R = 1.00 k and = 250 V in Figure P27.19,...Ch. 27 - In the circuit of Figure P27.20, the current I1 =...Ch. 27 - (a) Can the circuit shown in Figure P27.21 be...Ch. 27 - For the circuit shown in Figure P27.22, we wish to...Ch. 27 - An uncharged capacitor and a resistor are...Ch. 27 - Show that the time constant in Equation 27.20 has...Ch. 27 - In the circuit of Figure P27.25, the switch S has...Ch. 27 - In the circuit of Figure P27.25, the switch S has...Ch. 27 - A 10.0-F capacitor is charged by a 10.0-V battery...Ch. 27 - Show that the integral 0e2t/RCdtin Example 27.11...Ch. 27 - You and your roommates are studying hard for your...Ch. 27 - Prob. 30PCh. 27 - Turn on your desk lamp. Pick up the cord, with...Ch. 27 - Four resistors are connected in parallel across a...Ch. 27 - Find the equivalent resistance between points a...Ch. 27 - The circuit in Figure P27.34a consists of three...Ch. 27 - The circuit in Figure P27.35 has been connected...Ch. 27 - The resistance between terminals a and b in Figure...Ch. 27 - (a) Calculate the potential difference between...Ch. 27 - Why is the following situation impossible? A...Ch. 27 - When two unknown resistors are connected in series...Ch. 27 - When two unknown resistors are connected in series...Ch. 27 - The circuit in Figure P27.41 contains two...Ch. 27 - Two resistors R1 and R2 are in parallel with each...Ch. 27 - A power supply has an open-circuit voltage of 40.0...Ch. 27 - A battery is used to charge a capacitor through a...Ch. 27 - An ideal voltmeter connected across a certain...Ch. 27 - (a) Determine the equilibrium charge on the...Ch. 27 - In Figure P27.47, suppose the switch has been...Ch. 27 - Figure P27.48 shows a circuit model for the...Ch. 27 - The student engineer of a campus radio station...Ch. 27 - A voltage V is applied to a series configuration...Ch. 27 - The switch in Figure P27.51a closes when Vc23Vand...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- 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_forwardYour body is a moderately good conductor of electricity. Taken as a whole, your body's resistance measured for conduction from the fingers of one hand to the other is about 1500 ohms when the body is dry and typically 500 ohms when wet. The electric potential at a wall socket is 120 volts, so if you touch a high-potential house wire with one hand and ground with the other, the current through your body (dry) is approximatelyarrow_forward
- Whale 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_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_forwardMeasurements made during severe electrical storms reveal that lightning bolts can carry as much as 30 C of charge and can travel between a cloud and the ground in time intervals of around 100 μμs (and sometimes even shorter). Potential differences have been measured as high as 400 million volts. 1)What is the current in such a lightning strike? (Express your answer to two significant figures.) 2)What is the resistance of the air during such a strike? (Express your answer to two significant figures.) 3)How much energy is transferred during a severe strike? (Express your answer to two significant figures.) 4)What mass of water at 100∘C could the lightning bolt in part (3) evaporate? The latent heat of vaporization of water at 100∘C is LV=2260 kJ/kg. (Express your answer to two significant figures.)arrow_forward
- Consider a portion of a cell membrane that has a thickness of 7.50 nm and 1.8 pm x 1.8 um in area. A measurement of the potential difference across the inner and outer surfaces of the membrane gives a reading of 91.5 mV. The resistivity of the membrane material is 1.30 x 107n - m. (a) Determine the amount of current that flows through this portion of the membrane. (b) By what factor does the current change if the side dimensions of the membrane portion is halved? The other values do not change. O increase by a factor of 4 O decrease by a factor of 4 O increase by a factor of 2 o decrease by a factor of 8 O decrease by a factor of 2arrow_forwardA wire with resistance R is connected to the terminals of a 6.0 V battery. What is the potential difference ΔVends between the ends of the wire and the current I through it if the wire has the following resistances? (a) 1.0 Ω (b) 2.0 Ω (c) 3.0 Ω.arrow_forwardA copper wire of radius a = 0.330 mm has an aluminum jacket of outer radius b = 0.476 mm. There is a current i = 1.50 A in the composite wire. Take the resistivity for copper and aluminum to be 1.69 x 1080-m and 2.75 x 1080-m. Calculate the current in (a) the copper and (b) the aluminum. (c) If a potential difference V = 18.0 V between the ends maintains the current, what is the length in meters of the composite wire? (a) Number i (b) Number (c) Number i Units Units Unitsarrow_forward
- A rod of semiconducting material of Length L=2 m and cross-sectional area A=4 mm2 lies along the x-axis between x=0 and x=L. The material obeys ohm’s Law, and its resistivity varies along the rod according to ρ = ρ0*( 1 - x2/L2) where ρ0=3 x 10-4 Ω.m. The end of the rod at x=0 is at potential V0=25 V greater than the end at x=L. What is the electric potential, in units of volt, in the rod at x=L/2?arrow_forwardA certain resistor has a uniform cross-sectional area of 5.0 mm 2 and a resistivity of 2x10 -6 Ω-m. A 15-V electric potential is applied across the ends of the resistor causing a 4.0x10 -3 A current. Find (a) the resistance of the resistor and (b) the resistor’s length.arrow_forwardA straight, cylindrical wire lying along the x axis has a length of 0.500 m and a diameter of 0.200 mm. It is made of a material described by Ohm’s law with a resistivity of ρ = 4.00 x 10-8 Ω ⋅ m. Assume a potential of 4.00 V is maintained at the left end of the wire at x = 0. Also assume V = 0 at x = 0.500 m. Find (a) the magnitude and direction of the electric field in the wire, (b) the resistance of the wire, (c) the magnitude and direction of the electric current in the wire, and (d) the current density in the wire. (e) Show that E = ρJ.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning
Principles of Physics: A Calculus-Based Text
Physics
ISBN:9781133104261
Author:Raymond A. Serway, John W. Jewett
Publisher:Cengage Learning
Physics for Scientists and Engineers: Foundations...
Physics
ISBN:9781133939146
Author:Katz, Debora M.
Publisher:Cengage Learning
How To Solve Any Resistors In Series and Parallel Combination Circuit Problems in Physics; Author: The Organic Chemistry Tutor;https://www.youtube.com/watch?v=eFlJy0cPbsY;License: Standard YouTube License, CC-BY