# Recent content by resurgance2001

1. ### Hacked pulsed laser driver using Arduino

Try driving the laser with the transistor circuit on its own without the Arduino first and get that working. Lasers are dangerous to eyes period. No? Overdriving an diode is likely just to burn the thing out. Unless you are already staring at the laser I don’t see how this could be a...
2. ### Rod resting on a cylinder, find mu

Sorry I forgot to add the file.
3. ### Rod resting on a cylinder, find mu

Thanks. I have another answer that someone else has done. It looks like they are doing the right thing with what looks like possibly a good free body diagram. However, at the start of their answer they just seem to pull out of nowhere 1/2 NRC - I can’t see what the justification is for that...
4. ### Rod resting on a cylinder, find mu

My solution is on the files. The basic approac was the take moments about A. Then find the reaction at C. Use the reaction at C to find the friction between rod and cylinder. I take it to mean from the question that the friction between the rod and plane is equal to the friction between...
5. ### Index laws question

Thank you confirming that.
6. ### Index laws question

So then 0.5^x becomes 2^-x? So the two functions are effectively 2^x and 2^-x and because of this they are reflections of each other in the Y - axis. I don't know what else the teacher might be expecting but I suspect that the answer the teacher is looking for. What do you reckon? The...
7. ### Index laws question

Homework Statement we are asked to compare the graphs of 0.5^x with 2^x using index laws Homework Equations I am not sure how the regular index laws apply The Attempt at a Solution All I can say at the moment is the the graph of 2^x is a reflection of 0.5^x in the Y axis. I don't know...
8. ### A question about ionic bonding

Ok - that makes more sense now. Thanks
9. ### A question about ionic bonding

Yes - I have done questions about the Born-Haber cycle and I do appreciate the arguments about screening. I still struggling though to understand from the point of view of energy why the electron is actually transferred say from the sodium atom to the chlorine atom. Because what we are...
10. ### A question about ionic bonding

I am sure this question will have been asked elsewhere, so please forgive me if it has. My question involves the transfer of electrons in ionic bonding. We are told that a metal will give up its outer most electron because by doing so it will gain the electron configuration of a noble gas...
11. ### Statistics Permutations and Combinations

Perok - that was what I was trying to do. I think I can see now that the answer to that question is 11P7 x 2 and then we subtract that from the answer to part a) Thanks
12. ### Statistics Permutations and Combinations

Thanks - sorry about the bold font. It just picked it up from the template - I should have gone back to change it. I actually found that the way I did it got a correct answer. I had made a mistake in my calculation for part a) I will try your method also. The make scheme just said 11P7 x 2...
13. ### Statistics Permutations and Combinations

Homework Statement The back row of a cinema has 12 seats, all of which are empty. A group of 8 people including Mary and Francis, sit in this row. Find the number of ways they can sit in these 12 seats if a) There are no restrictions b) Mary and France's do not sit in seats which are next to...
14. ### Probability Question -- probability that no member will receive more than one of the medals

So the first factor of 15/15 which you said is not really necessary is just saying that there is a 15/15 or probability of 1 that one of the 15 will get the first meddle - which is trivial. Thanks
15. ### Probability Question -- probability that no member will receive more than one of the medals

Thank you - I think you have explained it very well and in the simplest terms.