×

Let's log you in.

or

Don't have a StudySoup account? Create one here!

×

or

Lab 2

by: Austin J Henry

27

1

3

Lab 2 Earth 3

Austin J Henry
UCSB

Get a free preview of these Notes, just enter your email below.

×
Unlock Preview

notes
COURSE
msa
PROF.
dr. jim
TYPE
Class Notes
PAGES
3
WORDS
CONCEPTS
tag
KARMA
25 ?

Popular in Earth Science

This 3 page Class Notes was uploaded by Austin J Henry on Friday March 25, 2016. The Class Notes belongs to Earth 3 at University of California Santa Barbara taught by dr. jim in Winter 2016. Since its upload, it has received 27 views. For similar materials see msa in Earth Science at University of California Santa Barbara.

×

Reviews for Lab 2

×

×

What is Karma?

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 03/25/16
Austin Henry 7874399 Wednesday 1—4 Eric Sandouk Charge to mass ratio of the Electron In this experiment we deduce the charge to mass ratio of the electron based on its deflection from a straight path under the influence of various magnetic fields. In this experiment we use a vacuum tube in the center of a pair of Helmholtz coils. Electrons are fired through a slit` parallel to the coils’ axis in low pressure to create a ribbon of electrons. This is made visible by a low concentration of mercury gas in the tube. This ribbon can then be deflected into an elliptical or circular path by running current through the coils, creating a magnetic field. The radii these paths form is measurable and the voltage controlled. Once the electron leaves the anode its energy will be entirely kinetic and 1 eq.1¿ mv =eV computable through the equation: 2 . V in this case is provided by the filament power supply and can be held constant. A magnetic field can then be introduced by the Helmholtz coils with its force acting perpendicular on the path of the electrons with the force computable by the equation: eq .2¿F=evB . For example, a charge of -2.6*10^ (-10) C moving at 10,000 m/s in the earth’s magnetic field experiences a force of 8.23*10^-11 N. Similarly, the force acting on the electron ribbon van be calculated. Using the two equations stated earlier, the charge to mass ratio of the electron can be found. The derivation of the equation used in this experiment is shown below mv 2 eq.3¿F= R Substituting F from eq. 3 into eq. 2 leads to: 2 mv R =evB mv =eB R eBR v= m e B R 2 v = 2 m Substituting this form of v^2 into eq. 1 leads to 2 2 2 1 m∗e B R =eV 2 m2 1 eB R2 =V 2 m Eq.3¿ e= 2V m B R 2 The value of B in tesla for the set of Helmholtz coils used in this experiment is: B=.00196 T ∗I ( A where I is the current measured by the coil power supply. The equipment used also includes a filament to supply a negatively charged electron cloud. An adjust-a-volt is attached to the filament power supply to ramp the current up from 0. The accelerating voltage, used to accelerate the electron cloud, is measured by an attached multimeter also used to adjust the accelerating voltage. This accelerating voltage is used to propel the electrons through a narrow slit into the vacuum chamber, forming a thin visible ribbon. The velocity of the electrons in this beam are computable from the known voltage measured by the multimeter in combination with Eq. 1). The Helmholtz coil circuit is then used to adjust the perpendicular magnetic force, used to bend the beams into a circular path. This measurable radius can be used with the other known or measurable elements of Eq. 3) to calculate the charge mass ratio of the electron. The results of our experiment are shown in the tables below: Helmholtz Accelerating B (Induced v (of Radius of e/m ratio, Coil Current, Voltage, V magnetic electron), Path (m) C/kg A field), T m/s 2.30 24.8 .032 238349313 0.004508 343833.2 3 1.97 “” .039 218729755 0.003861 329378.1 5 1.75 “” .045 208194095 0.00343 321347.6 7 1.45 “” .052 227105076 0.002842 335625 4 1.26 “” .057 250310306 0.00247 352354.8 6 2.77 30.1 .032 199445781 0.005429 346505.9 0 2.29 “” .039 196464537 0.004488 343906.5 3 2.95 “” 0.005782 231369.4 .045 889232422 1.68 “” .052 205333163 0.003293 351582.9 3 1.48 “” .057 220196903 0.002901 364085.9 0 3.01 35.0 .032 196405185 0.0059 370787.9 3 2.50 “” .039 191679940 0.0049 366300.4 5 2.08 “” .045 207986046 0.004077 381562.9 6 1.82 “” .052 203440040 0.003567 377369.9 7 1.62 “” .057 213700804 0.003175 386769.4 4 With my average e/m ratio equaling 2044176128 C/kg.

×

25 Karma

×

×

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Jim McGreen Ohio University

"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Amaris Trozzo George Washington University

"I made \$350 in just two days after posting my first study guide."

Steve Martinelli UC Los Angeles

Forbes

"Their 'Elite Notetakers' are making over \$1,200/month in sales by creating high quality content that helps their classmates in a time of need."

Become an Elite Notetaker and start selling your notes online!
×

Refund Policy

STUDYSOUP CANCELLATION POLICY

All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email support@studysoup.com

STUDYSOUP REFUND POLICY

StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here: support@studysoup.com

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to support@studysoup.com