# Search results

1. ### Interference - two wave source

Oh ok thank you again.
2. ### Interference - two wave source

Thankss for replying, can you explain in more detail what you meant? are you saying that the difference in wavelengths must be a whole number otherwise the formula won't work?

Thank you!
4. ### Interference - two wave source

Im sorry I didnt mean to get you upset or anything, but I wish to understand this fully for my upcoming test. They both arrive at 2.5 wavelengths so the interference is constructive I believe.
5. ### Interference - two wave source

In the presence of the building, you can fit 1 wavelength, in the absence you can fit only half. Let me see if I get this, assume we move the building to the very end of the 40m length. So up to 30m, there are 1.5 wavelengths, but when the wave enters the building, then it can 'fit' one...
6. ### Interference - two wave source

Thank you! you two are awesome, I am working on the one with the building, any help will be appreciated.
7. ### Interference - two wave source

I believe λ changes with respect to n right? so λ = λnot/n, so λ= 20m/2 so λ=10m, is this the wavelength when n=2? I dont know if there is 1 wavelength in the 10m building, or 1/2 of the original one. I am assuming is 1wavelength of the new wavelength. is this correct? well, one arrives 0.5...
8. ### Interference - two wave source

ok there is a right triangle there, so the distance from source 1 to P would be obviously 40m, and the distance from source 2 to P is 50m. The 40m represent 2 wavelengths and the 50m represent 2.5 wavelengths.
9. ### Interference - two wave source

lets see, c = f*lambda, so then, c/f = wavelength. 3.0*10^8 / 15*10^6 = lambda. So, lambda= 20m.
10. ### Interference - two wave source

Sorry, I totally forgot about this. Both sources are on phase and emit radiation of 15 MHz in every direction. Radiation is detected at point P. They also say that at P, source 1 delivers an average of 4*10^-4 W on a small square of 1cm^2 . I also have an extra question. Imagine that the...
11. ### Interference - two wave source

I do not know how to approach this. I am trying to use r1 - r2 = mλ but I cant seem to find the answer! please help. I figured it out that it is constructive, but i just dont know how to mathematically prove it. r1 - r2 = mλ.
12. ### AC circuits.

Oh ok thank you. I am trying to approach this problem in so many different ways that I got stuck already, So here is my attempt to solving this. 1. We know that if w increases, I increases. I = V/Z , so in order for I to increase, Z has to decrease (as V is constant). (holy crap my head is...
13. ### AC circuits.

Thank you, yes I forgot that they were actually giving me the RMS current. You mention something interesting though, the average current is zero. This is because the current oscillates between 20 and -20 right? so the average is 0. Just making sure I know my facts. Ty.
14. ### AC circuits.

EWell, there has to be only one element, so either Xc or Xl = 0, if one of the =0 then the other is present. Z = sqrt( R^2 + (Xl-Xc)^2), which is either sqrt( R^2 + Xl^2) or Sqrt( R^2 + Xc^2) , or simply sqrt(R^2 + X^2) where X is either 1/wC or wL. EDIT: In case you meant the actual value...
15. ### AC circuits.

thanks for replying! Ok, so the impedance for both would be Z = sqrt ( R^2 + X^2) , where X can be either the impedance of a capacitor or an insulator. So for a capacitor, Z = sqrt ( R^2 + (1/wC)^2) and for the insulator Z = sqrt(R^2 + (wL)^2)... ok I see now how the angular frequency would...
16. ### AC circuits.

Sorry, here it is. Ty.
17. ### AC circuits.

Hi, so I have a homework problem and I don't know how to approach. I am given a circuit, with an AC source, a resistor ( 2 Ω) and a unknown circuit element (that could be an inductor or a capacitor). I am also given a graph with the Voltage amplitud across the AC source (Which happens to be...
18. ### R-L Circuit, Finding the current through a circuit element.

ok that was really helpful. Thank you Rude man! hehe
19. ### R-L Circuit, Finding the current through a circuit element.

Oh Yeah! They are connected in parallel, so the Potential across the inductor must be equal to the potential across the 20 ohm resistor, if that is the case then the potential across the resistor is 0, from Ohm's law, 0=I.R, so I must be zero as well... Is this correct? Why is the current 0? I...
20. ### R-L Circuit, Finding the current through a circuit element.

Homework Statement So I am having a hard time trying figuring this out. The question asks for the current through the 20Ω resistor as well as the current through the battery AFTER THE SWITCH HAS BEEN CLOSE FOR ALONG TIME. Here is a picture of the circuit. http://i.imgur.com/VjoFSUd.jpg...

Thanks!
22. ### Moving Square Loop through a Magnetic Field

So let me see if I get this right, as soon as some of the magnetic field area gets inside the loop, there is a magnetic flux through the coil, which will be B *A, here the area will be the area from the little square THAT IS INSIDE THE LOOP, so the flux = 4T*y*x Since height is constant cause...
23. ### Moving Square Loop through a Magnetic Field

wouldn't that integral become B*A since B and the vector dA are parallel? why do you mean by 'They tell you where B is zero, and where B is 4T, so you need to use this information to do the integral properly' Thanks alot for your help!
24. ### Moving Square Loop through a Magnetic Field

I am very confused now, I thought they were asking for the magentic flux through the area of the coil (loop shown in red) so the area of the coil would be just 1.5^2. If that is the case, then the magentic flux will be that area times the field (4T) but the field is not changing so the flux is...
25. ### Moving Square Loop through a Magnetic Field

Homework Statement A square loop of side 1.5m and Resistance 2Ω is pulled with a constant velocity v=0.3m/s through a smaller region with a constant magnetic field B (out of the page) of 4T. The figure shows the position at t=0. Calculate the magnetic flux of the coil at t=4s.. Here is a...
26. ### Rotation of a Rigid Body

wait, how come it only drops 1 meter? i thought it was gonna hit the ground? are you saying that it doesnt actually hit the floor?..... how come i got the same answer then? sorry but that made me confused... EDIT! OH OH! sorry i got 2m because i multiplied both sides of the last equation by 2...
27. ### Rotation of a Rigid Body

thanks! and sorry about that! Yes it is kinda confusing but im happy to know that someone else got the same acceleration. Well, I tried applying the kinematic formula: yf = yi + Vi*t + 1/2 a t^2 ... t = delta t... and i chose the initial point to be 0, so the final point would be -2m since...
28. ### Kinetic and Rotational energy of a sphere

hey bro, thanks for helping me, the answer was indeed 2/7 .. but can you explain me how you got that answer?
29. ### Rotation of a Rigid Body

Homework Statement The two blocks in the figure are connected by a massless rope that passes over a pulley. The pulley is 14cm in diameter and has a mass of 2.4 kg. As the pulley turns, friction at the axle exerts a torque of magnitude 0.54 Nm . Homework Equations so m1 = 4.0kg m2= 2.0 kg M...
30. ### Kinetic and Rotational energy of a sphere

ok, i dont know what that means then, i thought you had to get the ratio between them,,, if so then i am getting 0.30, which is supposed to be wrong...