PCS 125 Chapter Notes - Chapter 3: Current Density, Thermal Velocity, Ampere

19 views12 pages

mauvefish953

3 Aug 2018

School

Department

Course

Professor

For unlimited access to Textbook Notes, a Class+ subscription is required.

Document Summary

The rate of flow of charge through any cross-section of a wire is called electric current flowing through it. Electric current (i) = q / t. its si unit is ampere (a). The conventional direction of electric current is the direction of motion of positive charge. The current is the same for all cross-sections of a conductor of non-uniform cross-section. Similar to the water flow, charge flows faster where the conductor is smaller in cross-section and slower where the conductor is larger in cross-section, so that charge rate remains unchanged. According to its magnitude and direction electric current is of two types (i) direct current (dc) its magnitude and direction do not change with time. A ceil, battery or dc dynamo are the sources of direct current. (ii) alternating current (ac) an electric current whose magnitude changes continuously and changes its direction periodically is called alternating current.

Related Questions

Consider an electric dipole whose dipole moment (a vector pointing from the negative charge to the positive charge) is oriented at an angle with respect to the y-axis. There is an external electric field of magnitude E (independent of the field produced by the dipole) pointing in the positive y-direction. The positive and negative ends of the dipole have charges +q and -q, respectively, and the two charges are a distance d apart. The dipole has a moment of inertia I about its center of mass. It will help you to imagine that the dipole is free to rotate about a pivot through its center.

A) What is the net force that the dipole experiences due to the electric field?

B) What is , the magnitude of the torque that the electric field exerts about the center of mass of the dipole?

C) Using the above result, find the potential energy associated with the dipole's orientation in the field as a function of the angle shown in the figure. Take the zero of the potential to occur when the dipole is at angle ; that is , .

D) In terms of the dipole moment , What is the expression for the torque on a dipole in the field ?

E) In terms of the dipole moment, What is the expression for the potential energy of a dipole in the field?

redmammoth521

Please show work for each question so I know how todoit.

A charge of +2C is at the origin. When a charge Q is placed at2malong the positive axis, the electric field at 2m along thenegativex axis becomes zero. What is the valueofQ? a.-3C b.-6C c. - 7C d. -8C

8. Electrons in a particle beam each have a kinetic energyof3.2x10-17 J. What is the magnitude of the electric field thatwillstop these electrons in a distance of 0.1m?

a. 200 N/C b.1000N/C c. 2000N/C d. 4000N/C

9. A proton (+1.6x10^-19 C) moves 10cm along the direction ofanelectric field os strength 3.0 N/C. The electricalpotentialdifference between the protonâs initial and endingpointis:

a. 4.8x 10^-19 V b.0.30V c.0.033V d. 30V

10. If an electron is accelerated from rest through apotentialdifference of 1200V, find its approximate velocity at theend ofthis process. ( e= 1.6x10^-19 C, m= 9.1x10^-31kg)

a.1,0x10^7m/s b.1.4x10^7m/s c.2.1 x10^7m/s d.2.5x10^7m/s

) Ion Rocket Engine. A special type of rocket engine useselectricity for propulsion: the ion engine. A soft metal, such ascesium, is vaporized and then electrified (ionized) with highvoltage. These cesium ions are the accelerated by strong electricfields to produce a current of atoms at high velocity. Outside theengine, the ions are then recombined with electrons to restoreelectrical neutrality.

A particular ion engine has an exhaust velocity of 20,000 m/sec.The mass flow (dm/dt) is just 1 milligram per second.

a) What is the thrust produced by this engine?

b) The engine propels a 200 kg spacecraft. What velocity change(delta-v) is achievable by running the engine continuously for onesolid year? (For simplicity, assume a constant mass for the system.One year = 31.56 million seconds.)
---------------------------
) Potential Energy. How much work is required to lift one metricton (1000 kg) of water to an altitude of 1000 meters? (The Sun isdoing this all this time to the Earthâs weather.)
--------------------------------

q) Kinetic Energy 1. A car has a mass of 1200 kg. How much kineticenergy does it have when traveling at a speed of 30 m/sec?

-----------------------
Kinetic Energy 2. The Space Shuttle orbits the Earth at a speed ofsome 7750 meters per second (which is about 260 times that of atypical highway driving speed). With a typical payload, the Shuttlehas a mass of 120,000 kg.

a) What is the kinetic energy of the Shuttle in orbit?
b) The Shuttle reaches orbit in some 500 seconds. At what rate ofwork (power) did the rocket engines perform on the Shuttle to placethe craft and its payload into orbit? Compare this to the maximumpower output of a typical nuclear electric generatingstation.
-----------------------

Solar Power. In space, outside the atmosphere, some 1360 Watts ofradiant power pass through every square meter (at normalincidence).

a) What total amount of power does the Earth intercept from theSun? (The projected area of the Earth is ?RE2, where RE is theradius of the Earth, 6.38 million meters.)

b) Compare this figure to the total amount of power produced by allof human civilization, currently some 40 trillion (1012) Watts.What conclusions about solar power can you draw from thiscomparison?

q

-) Angular Momentum. Assuming a uniform distribution of mass insidethe Earth, calculate:

a) the Earthâs moment of inertia, I;
b) its angular momentum, L = omega(omega=2pi/T) the angularmomentum of the Moon in its orbit around the Earth (L = mvr).Compare these two values. (The sidereal period of the Moon is 27.3days; its mass is 1/81 of that of the Earth; its average orbitalradius is 383,000 km.)

------------------------------------

Q0 Water Pressure. Calculate the value of the water pressure at theChallenger Deep, the deepest known place on the surface of theEarth. The currently accepted depth of the water there is 10,911meters. (This is deep enough to cover Mount Everest, and still havemore than one mile of water above the peak. On January 23, 1960,Swiss explorer Jacques Piccard and US Navy Lieutenant Don Walshbecame the first, and so far, the only people ever to visit thisremote place, descending in the Italian-built bathyscaphTrieste.)

q-8
Mass of Earthâs Atmosphere. The pressure of the Earthâs atmosphereat sea level is 101,300 Pascals (Newtons per square meter.) Thismeans that every square meter of Earthâs surface supports a weightof 101,300 Newtons. From this, determine the mass of Earthâsatmosphere. What fraction of the Earthâs total mass is this?

PCS 125 Chapter Notes - Chapter 3: Current Density, Thermal Velocity, Ampere

Document Summary

Get access

Related textbook solutions

Physics: Principles with Applications

Related Documents

PCS 125 Chapter Notes - Chapter 6: Electromagnetic Induction, Electrical Network, Electrical Resistance And Conductance

PHYS 012A Lecture Notes - Lecture 14: Drift Velocity, Charge Carrier, Electric Potential Energy

PHYS 1B Chapter 21: Textbook Notes

Related Questions