Chemical analysis of a silicon crystal reveals gallium at a level of 3.091×10−4 atomic percent. Assuming that the concentration of thermally excited charge carriers from the Si matrix is negligible, what is the density of free charge carriers (free carriers/cm3) in this Si crystal?
Calculate the surface energy of the (100) surface of niobium. The enthalpy of atomization of niobium is 745 kJ/mole. Express your answer in units of J/cm2.
A formation energy of 1.11 eV is required to create a vacancy in a particular metal. At 777oC there is one vacancy for every 22,200 atoms. At what temperature will there be one vacancy for every 11,100 atoms?
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A photon interacts with a ground state electron in a hydrogen atom and is absorbed. The electron is ejected from the atom and exhibits a de Broglie wavelength of 0.468×10−10 m. Determine the frequency (in hz) of the interacting photon.
Help me i need science help
Help me i need science help Its all about sedimentary and metamorphic rocks
2) What do you think the appearance of a roc tells us about the chemicals which make up these rocks?
3) Describe how you are able to match sedimentary rocks to their children rocks (metamorphic)?
4) Take a piece of limestone and squeeze it. Where do you think there is enough pressure to change this sedimentary rock into a metamorphic rock?
5) The metamorphic rocks in the Lake District, California and Mt Everest have all been changed by heat and pressure. Explain why the rock types found in these 3 places are different.
if you dont know anything, please help with keeping it active!
i have to reasearch magnetism, so i need to know what the following mean,BY THE WAY, sorry it's long; -drag -water+air resistance -non'contact force -electro magnet -north-seeking pole thanks guys:)
Hi i have to do a Lab report i am in year 8 i have completed need some more assistance and checking.
Identify which concepts/topics you believe that you will need to apply to solve the problem below. Select all that apply.
Covalent Bond Energy
Ionic Bond Energy
Single-electron Atom Ionization Energy
Multi-electron Atom Ionization Energy
Conservation of Energy
For the emission spectrum of Be3+, calculate the lowest wavenumber νˉ (in inverse meters) of light produced by electron transitions between n=2, n=3, and n=4.
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Explain with diagrams and using particle theory the journey of a skydiver and the parachute.
For my science homework I have to complete a sheet on the effects of smoking. There are a couple of questions that I am really struggling with please could you help? These are the questions:
- Describe what effect the loss of surface area would have on the health of a smoker?
- Describe what effect the blocked cilia would have on the health of a smoker?
Thanks a lot! X
Science Force Homework :(
Lorna is better in a game of rounders. She hits the ball. The bat puts a force on the ball. Using the information given above, write down three effects that the force has on the ball. Whats the answer I was off at school when they did that and the teacher still makes me do the homework 🙁