Recent content by wendo

Hi! I hope I'm posting in the right place! In the destructive interference of waves and solving for the path difference, I"m confused at when we should use m+1/2 vs. m-1/2 ( so the eq'n is PD=(m+1/2)lambda or PD=(m-1/2) lambda Any insight would be greatly appreciated! :) thanks!

Thanks astronuc for your reply! The question gives the counting efficiency and overall asking to calculate the age of a piece of wood. So in this case if counting efficiency is 85.7%, and 845 counts are accumulated in one week, then .857=845 per week/# of beta particles actually...

Beta particle counting efficiency?? Hi! Can anyone tell me what counting efficiency means? For example if it's put into a question as: "shielded beta counter with 85.7% counting efficiency, 845 counts are accumulated in one week" what does it mean? How I understand it so far is that it's...

Homework Statement An electron has a velocity of 1.63×104 m/s (in the positive x direction) and an acceleration of 1.98×1012 m/s2 (in the positive z direction) in uniform electric and magnetic fields. If the electric field has a magnitude of 19.8 N/C (in the positive z direction), what is...

Using an arbitrary area worked! THANK YOU SOOOOOO MUCH! (i'm going to warn you now that i might have a lot of questions today...) So the voltage will be the same regardless of what the area is, but in order to keep it the same the charge on the plates will change. I see! I was just really...

Homework Statement Two parallel plates having charges of equal magnitude but opposite sign are separated by 14.2 cm. Each plate has a surface charge density of 33.3 nC/ m2. A proton is released from rest at the positive plate. Determine the potential difference between the plates...

Is there a value for epsilon in the equation: k=1/4pi-epsilon?

I got it! THANK YOU for your help!

hmm, okay so if I break down the forces to all the components, it seems to me that the vertical forces would cancel out and only the horizontal forces remain, but I'm not 100% sure. (my reasoning is that because its in equlibrium then all the forces in opposite directions would cancel out...

Homework Statement A small m=1.70×10-3 kg plastic ball is suspended by a l=20.0 cm long string in a uniform electric field, as shown below. If the ball is in equilibrium when the string makes a θ=13.1° angle with the vertical, what is the net charge on the ball? Take E=1.04×103i N/C...

I ran out of tries and I still didn't get the question right.. :( In this case, would the outer radius matter more because that's where most of the mass is concentrated? I really had trouble thinking about this because if you decrease the inner radius (ie. bring more of the mass to...

Thank you for your replies! What both of you are saying makes sense, finding angular speed is definitely much easier with v=wr, but which radius would I use? the inner, outer or a total of both? I tried to solve the problem again using the approaches that you suggested but I'm still not...

Homework Statement A ring of mass 2.83 kg, inner radius 5.30 cm, and outer radius 6.95 cm rolls (without slipping) up an inclined plane that makes an angle of θ=37.4°, as shown in the figure below. http://capa.physics.mcmaster.ca/figures/sb/Graph11/sb-pic1106.png At the moment the ring...

omg... wow... I can't that was all it was! THANK YOUUU DICK! :D

Homework Statement An electron is projected at an angle of 31.7° above the horizontal at a speed of 8.40×10^5 m/s in a region where the electric field is E = 383j N/C. Neglecting the effects of gravity, calculate the time it takes the electron to return to its initial height. Homework...