Learning Materials
Features
Discover
Chapter 2: Q45P (page 45)
In gold at room temperature, the mobility of mobile electrons is about , and there are about mobile electrons per cubic meter. Calculate the conductivity of gold, including correct units.
The conductivity of gold is .
Over 30 million students worldwide already upgrade their learning with 91影视!
All the tools & learning materials you need for study success - in one app.
Get started for free
Question: the Hall effect can be used to determine the sign of the mobile charges in a particular conducting material. A bar of a new kind of conducting material is connected to a battery as shown in Figure 20.85. In this diagram, the x-axis runs to the right, the y-axis runs up, and the z-axis runs out of the page, toward you. A voltmeter is connected across the bar as shown, with the leads placed directly opposite each other along a vertical line. In order to answer the following question, you should draw a careful diagram of the situation, including all relevant charges, electric fields, magnetic fields, and velocities.
Initially, there is no magnitude filed in the region of the bar. (a) Inside the bar, what is the direction of the electric field due to the charges on the batteries and the surface of the wires and the bar? This is the electric field that drives the current in the bar. (b) If the mobile charges in the bar are positive in what direction do they move when the current runs? (c) If the mobile charges in the bar are negative, in what direction do they move when the current runs? (d) In this situation (zero magnetic fields), what is the sign of the reading on the voltmeter?
Next, large coils (not shown) are moved near the bar. And current runs through the coils, making a magnetic field in the -z direction (into the page). (e) If the mobile charges in the bar are negative, what is the direction of the magnetic force on the mobile charge? (f) If the mobile charges in the bar are negative, which of the following things will happen? (1) Positive charge will accumulate on the top of the bar. (2) The bar will not becomes polarized. (3) Negative charge will accumulate on the left end of the bar. (4) Negative charge will accumulate on the top of the bar. (g) If the mobile charges in the bar are positive, what is the direction of the magnetic force on the mobile charges? (h) If the mobile charges in the bar are positive, which of these things will happen? (1) positive charge will accumulate on the top of the bar. (2) The bar will not becomes polarized. (3) Positive charge will accumulate on the right end of the bar. (4) Negative charge will accumulate on the top of the bar.
You look at the voltmeter and find that the reading on the meter is . (i) What can you conclude from this observation? (Remember that a voltmeter gives a positive reading if the positive lead is attached to the higher potential location.) (1) There is not enough information to figure out the sign of the mobile charges. (2) The mobile charges are negative. (3) The mobile charges are positive.
The performance of two different cars, car 1and car 2, was measured on a long horizontal test track. Car 1started from rest and ran with constant acceleration until it was halfway down the track and then stopped accelerating, continuing to run at the attained speed to the end of the track. Car 2started from rest and ran with a constant acceleration for the entire distance. It was observed that both cars covered the test distance in the same amount of time. (a) What was the ratio of the average speed of carto that of car 2? (b) What was the ratio of the initial acceleration of car 1to that of car 2? (c) What was the ratio of the final speed of car 1to that of car 2?
In a lab experiment you observe that a pendulum swings with a "period" (time for one round trip) of . In an iterative calculation of the motion, which of the following would NOT be a reasonable choice for , for either hand or computer iterative calculations? a) b) c) d)
If you did not already to problem P60, do it now. Also calculate numerically the angle through which the yo-yo turns, in radians and degrees.
In a lab experiment you observe that a pendulum swings with a 鈥減eriod鈥� (time for one round trip) of . In an iterative calculation of the motion, which of the following would NOT be a reasonable choice for , for either hand or computer iterative calculations? a) b) c) d) .
What do you think about this solution?
We value your feedback to improve our textbook solutions.
Explanations 
Textbooks 
Flashcards 
91影视 AI 
Notes 
Study Plans 
Study Sets 
Find a degree 
Magazine