Physics 1029A/B Lecture Notes - Lecture 8: Cirrhosis, Plasma Cell, Globulin

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greenduck439

29 Dec 2015

School

Western University

Department

Physics

Course

Physics 1029A/B

Professor

Martin Zinke- Allmang

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Document Summary

Physics lecture 16 electric energy, parallel plates. Is introduced in the same fashion as all other forms of energy were introduced before o: with work given as: w = epotentional, final epotential,initial. We consider again: single point charge (ions in solution, dipole (water molecule, hydration shells, charged parallel plates (nerve membranes) E = cont f = const (not position dependent) Electric energy for a test charge between charged parallel plates o: assume qtest is a positive charge o, w = epotential,final epotential,initial o. Example electropheresis is the transport of charged particles in a solution caused by electric forces acting on the particle between two charged parallel plates. Set up to separate dna fragments across a gel after dna has ben cut into fragments by restriction enzymes. This is an application from forensic science: a single globulin molecule moves 7 cm toward the negative plate during an electrophoresis separation in an electric field of.

Related Questions

A parallel-plate vacuum capacitor is connected to a battery and charged until the stored electric energy is

. The battery is removed, and then a dielectric material with dielectric constant

is inserted into the capacitor, filling the space between the plates. Finally, the capacitor is fully discharged through a resistor (which is connected across the capacitor terminals).

A.)Find

Image for A parallel - plate vacuum capacitor is connected to a batteryand charged until the stored electric energy is U_r

, the energy dissipated in the resistor.

Express your answer in terms of

and other given quantities.

B.) Consider the same situation as in theprevious part, except that the charging battery remains connected while the dielectric is inserted. The battery is then disconnected and the capacitor is discharged. For this situation,what is

, the energy dissipated in the resistor?

Express your answer in terms of

and other given quantities.

peachwildebeest710

To practice Problem-Solving Strategy 21.1 Conservation of energy incharge interactions.

An alpha particle (), which is the same as a helium-4 nucleus, ismomentarily at rest in a region of space occupied by an electricfield. The particle then begins to move. Find the speed of thealpha particle after it has moved through a potential difference of-3.45Ã10-3 .
The charge and the mass of an alpha particle are = 3.20Ã10-19 and =6.68Ã10-27 , respectively.

PROBLEM-SOLVING STRATEGY Conservation of energy in chargeinteractions

PREPARE Draw a before-and-after visual overview. Define symbolsthat will be used in the problem, list known values, and identifywhat you're trying to find.

SOLVE The mathematical representation is based on the law ofconservation of mechanical energy:

.

Find the electric potential at both the initial and finalpositions. You may need to calculate it from a known expression forthe potential, such as that of a point charge.
and are the total kinetic energies of all moving particles.
Some problems may need additional conservation laws, such asconservation of charge or conservation of momentum.
ASSESS Check that your result has the correct units, is reasonable,and answers the question.

Prepare
Identify the system involving the alpha particle. Then examine theforces acting within this system to determine whether mechanicalenergy is conserved. Make certain to draw a before-and-after visualoverview and to define your symbols.
Part A
Mechanical energy is conserved in the presence of which of thefollowing types of forces?
Select all that apply.
? frictional
? electrostatic
? magnetic
? gravitational

Which of the following quantities are unknown?
? the value of the electric potential at the initial position ofthe alpha particle
? the final speed of the alpha particle
? the charge of the alpha particle
? the mass of the alpha particle
? the difference in potential between the initial and finalpositions of the alpha particle
? the value of the electric potential at the final position of thealpha particle
? the initial speed of the alpha particle

1.Two uncharged, conducting spheres, A and B, are held at rest oninsulating stands and are in contact. A positively charged rod isbrought near sphere A. While the rod is in place, the two spheresare separated. How will the spheres be charged, if at all, afterthey are separated?
Sphere A Sphere B
(a) positive positive
(b) positive negative
(c) negative positive
(d) negative negative
(e) zero zero

2. A charged conductor is brought near an uncharged insulator.Which one of the following statements is true?
(a) Both objects will repel each other.
(b) Both objects will attract each other.
(c) Neither object exerts an electrical force on the other.
(d) The objects will repel each other only if the conductor has anegative charge.
(e) The objects will attract each other only if the conductor has apositive charge.

3. An electron is moved from point A, where the electric potentialis VA = â240 V, to point B, where the electric potential is VB =â360 V. What is the change in the electric
potential energy?
(a) 1.92Ã10â17 J (b) 2.04Ã10â17 J (c) 5.75Ã10â17 J (d) 8.98Ã10â17 J(e) 1.05Ã10â16 J

4. A -2q charge is located a distance d to the right of a +4qcharge, along the x
axis. At which point (or points) along the axis does the electricfield go to zero? To
solve this problem, consider an observer at point P, which is anarbitrary distance x from the +4q charge. Find the value (orvalues) for x (in terms of the separation distance d) where thetotal electric field vanishes.
(a) The electric field is never zero in the vicinity of thesecharges.
(b) The electric field is zero at x = -0.328d.
(c) The electric field is zero at x = +4.22d.
(d) The electric field is zero at both x = -2.26d and x =+2.26d.
(e) The electric field is zero at x = +3.41d.

5. point A is a distance L away from a point charge Q. Point B is adistance 4L away from Q. What is the ratio of the electrostaticpotential at B to that at A, i.e., what is VB/VA?
(a) 1/16
(b) 1/9
(c) 1/4
(d) 1/3
(e) can not be determined without specifying Q and L

6. Which one of the following statements best explains why it ispossible to define an electric potential
in a region of space that contains an electric field?
(a) Work must be done to bring two positive charges closertogether.
(b) Like charges repel one another and unlike charges attract oneanother.
(c) A positive charge will gain kinetic energy as it approaches anegative charge.
(d) The work required to bring two charges together is independentof the path taken.
(e) A negative charge will gain kinetic energy as it moves awayfrom another negative charge.

Physics 1029A/B Lecture Notes - Lecture 8: Cirrhosis, Plasma Cell, Globulin

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