Please help me finish lab...my lab stopped working and I can'tget the labs to finish. I highlighted and underlined my answers. Ibolded the questions that I could not finish.
1-4: Investigating the Properties of Alpha and BetaParticles
As scientists began investigating the properties of atoms, theirfirst discovery was that they could extract
negatively charged particles. They called these particleselectrons, but they are also known as beta
particles in the context of nuclear decay. Robert Millikan usedbeta particles in his famous Oil Drop
Experiment. Another particle ejected during nuclear decay is thealpha particle. An alpha particle is a
helium nucleus, or a helium atom without its two electrons.Consequently, an alpha particle is positively
charged. Ernest Rutherford used alpha particles in his Gold FoilExperiment.
1. Start Virtual ChemLab and select Alpha and BetaParticles from the list of assignments. The lab will open inthe Quantum laboratory.
2. What source is used in this experiment? Drag yourcursor over the source to identify it.
ElectronGun
What type of charge do electrons have? Negative
What detector is used in this experiment? A phosporScreen
3. Turn on the Phosphor Screen. (Click on the green/redbutton.)
What do you observe? A dot in the center of thescreen
The phosphor screen detects charged particles (such aselectrons) and it glows momentarily at the positions where theparticles impact the screen.
4. Drag the lab window down and left and the phosphor screenwindow up and right in order to
minimize the overlap. Push the Gridbutton on the phosphor screen, and set the Magnetic Fieldto 30
?T. (Click the button above the tens place three times. If youmistakenly click between digits, it will
move the decimal point. Click it to place it where it wasoriginally and then click above the tens
place.)
What happens to the spot from the electron gun on thephosphor screen? the dot moves to theright
5. Click once above the tens place on the ElectricField meter. Observe the spot. Click a second time
above the tens place on the Electric Field.
What happens to the spot from the electron gun on thephosphor screen? The dot moves to theleft
6. Zero out the Magnetic Field and ElectricField meters by clicking on the appropriate digit buttonsuntil the spot on the phosphor screen is centered again.
7. Double-click or click and drag the electron gun to move it tothe Stockroom counter. Enter the Stockroom byclicking inside the Stockroom. Double-click the electrongun to move it back to the shelf. Double-click on the alpha sourceto select it and move it to the Stockroom counter. Clickon the green Return to Lab arrow to return to the lab.Drag the alpha source from the Stockroom counter and placeit on the table where the electron gun was originally placed (themiddle spot light). Click on the front of the alpha source to openthe shutter.
What appears on thephosphor screen?
Atomic Theory
8. Change the unit for the Magnetic Field from ?T to mTby clicking once above the unit. Click above the hundreds placethree times to set the Magnetic Field to 300 mT(millitesla). This magnetic field is one million times strongerthan what we used for the electron gun.
Whichdirection is the spot deflected when the magnetic field isincreased this time?
How doesthis compare with the direction of movement when the magnetic fieldwas turned on for the electrons?
9. Change the unit for the Electric Field from V to kVby clicking once above the unit. Observe the spot as you increasethe Electric Field strength from 0 kV to 5 kV. Themovement is slight so pay careful attention.
Whichdirection is the spot moved when you increase the ElectricField?
How doesthis compare with the direction of movement for the electron beamin the Electric Field?
Why does ittake significantly stronger magnetic and electric field strengthsto move the beam of alpha particles compared with the beam ofelectrons (beta particles)?
10. Return the values on the two meters to zero. Double-click(or click and drag) the alpha source and the phosphor screen toreturn them to the Stockroom counter. Enter theStockroom. Double-click on the alpha source and thephosphor screen to place them on the shelf. Select the laser andthe video camera by double-clicking on them, and then click on thegreen Return to Lab arrow to return to the lab. Place thelaser in the center spotlight on the left and turn the laser on(click on the red/green light). Place the video camera on thecenter spotlight on the right and click the video camera to turn iton. Set the laser intensity to 1 nW and the wavelength to 20 nm.This wavelength is in the x-ray region of the electromagneticspectrum. The purple dot is a representation of the x-rays hittingthe video camera. Change the Electric Field andMagnetic Field to determine the effect on the x-rays.
Did theelectric or magnetic fields affect the x-rays? Why or whynot?
Summarizewhat you have learned about electrons (beta particles), alphaparticles, and x-rays.
