Recent content by Plasmosis1

Homework Statement Using Kelvin’s circulation theorem, find the qualitative and quantitative relation between the circulation around an airfoil and the circulation of the starting vortex. Homework Equations Kelvin's circulation theorem: DΓ/Dt=0 The Attempt at a Solution I don't really know...

No one actually said this but because ne<<nh you can just neglect ne. The original equation becomes: σ=|e|*nh*μh =1.6*10-19*3*1024*.007 =3360 (Ωm)-1

Is the equation ne*nh=(1.5x1010cm-3)2 where ni=1.5x1010cm-3 So ne=1.5*1010*1003m-3/(3*1024)=1.5*1016m-3 ∴ σ=1.6*10-19*(1.5*1016*0.03+3*1024*0.007)=3360 (Ωm)-1 Is that right?

The only other formula that I can think of is n=n0exp(-Eg/2kT) But I can't use that because I don't know n0 or Eg.

Homework Statement Estimate the electrical conductivity, at 135°C, of silicon that has been doped with 3 x 1024 per meter cubed of aluminum atoms. Assume values for electron and hole mobilities of 0.03 and 0.007 m2/V-s, respectively. Homework Equations σ=|e|(ne*μe+nh*μh)...

Homework Statement You want to photograph a circular diffraction pattern whose central maximum has a diameter of 1.2cm . You have a helium-neon laser (λ=633nm) and a 0.13-mm-diameter pinhole. How far behind the pinhole should you place the viewing screen? Homework Equations Y = λx/b...

Homework Statement A 0.42 -mm-diameter hole is illuminated by light of wavelength 510nm. What is the width (in mm) of the central maximum on a screen 1.8m behind the slit? Homework Equations f=λx/s The Attempt at a Solution I tried two answers, 4.4mm and 2.2mm and they are both...

Homework Statement A 10-cm-diameter parallel-plate capacitor has a 1.0 mm spacing. The electric field between the plates is increasing at the rate 1.4×106V/m*s. What is the magnetic field strength 2.7cm from the axis? Homework Equations \ointB*ds=\mu\epsilondE(t)/dt*A...

Homework Statement A point charge q is situated a distance d/2 above a square surface of side d as shown (see attached). a) It cannot be determined b) 2q/ε0d c) q/4\piε0 d) q/\piε0d2 e) q/6ε0 Homework Equations \Phi=qenc/ε0=\ointE*dA The Attempt at a Solution Shouldn't the...

Ok so AB bisects angle CBD. If you make AB the x-axis CB and DB will be 28-11=17 degrees above and below the x-axis. The two x-component of the two will add up to 395 so the x component of one of them is 395/2=197.5. So the tension is 197.5/cos(17)=207N. Thanks!

I just attached a FBD of the pulley but it doesn't really help much. I don't know any of the angles for BD so I don't know how to account for the forces with it.

Ok but that still doesn't help me with solving for the force in CBD. Can someone walk me through the steps please?

Homework Statement Due to settlement of soil, a recently planted tree has started to lean. To straighten it, the cable system shown is used, where a turnbuckle on cable AB is periodically tightened to keep the cable taut as the tree gradually straightens. If the force in cable AB is 395 N...

What is the radius of the de broglie circular orbit with n=1?

"one if by land and two if by sea" is the famous saying of Paul Revere when he was a certain distance away from a signal sent from the people of old North Church in Boston on the night of April 18, 1775. if the average human pupil has a diameter of 4mm at night and the lanterns had a predominant...