# Search results

1. ### Dispersion by diffraction grating

Please help, I only have a couple of hours left.
2. ### Dispersion by diffraction grating

That's the equation I'm used to. If we assume that the angle is small then sintheta=y/L dsintheta=m*wavelength d(y/L)=m*wavelength m*wavelength*L/(d)=y ? I don't know what's wrong with the equation. For the units I coverted everything to cm because 1/7300=d in cm.
3. ### Dispersion by diffraction grating

Homework Statement White light containing wavelengths from 396 nm to 756 nm falls on a grating with 7300 lines/cm. How wide is the first-order spectrum on a screen 2.15 m away? Homework Equations y=m*L*wavelenth/(d) The Attempt at a Solution using the equation I have found y1 to...
4. ### Induced emf at a specific time

Thank you very much I appreciate it.
5. ### Induced emf at a specific time

Could you please tell me where I'm wrong? I have a couple of hours left.
6. ### Induced emf at a specific time

I plugged in -36.12 but it's still wrong. Can we have a negative voltage?
7. ### Induced emf at a specific time

Homework Statement A circular coil with 35 turns of wire and a diameter of 19 cm is placed in a magnetic field given by B(t) = 6 t^2 + 6 t + 2 T where t is time in seconds. The field is perpendicular to the plane of the coil. What is the induced EMF at t = 5 s? Homework Equations...
8. ### Time required to charge a capacitor

Homework Statement A capacitor with a capacitance of C = 28.7 μF is slowly charged by a constant current of I = 63.2 nA. How long does it take to charge the capacitor to a voltage of V = 28.9 V? Homework Equations q=cvb(1-e^(-t/RC)) Vb=IR+QC The Attempt at a Solution I have tried...
9. ### Voltage experience by the bird

I thought that was the equation for voltage loss. Is it not?
10. ### Voltage experience by the bird

Ok so I got it by using voltage loss=amps*wire resitance/meter*distance Usually this equation is voltage loss=amps*wire resitance/meter*distance*2 wires Why was it not necessary to multiply the answer by 2 in this case?
11. ### Short circuit problem

R=sigma(x)/A, but area is not given either. I really don't understand.
12. ### Voltage experience by the bird

Homework Statement A bird stands on an electric transmission line carrying 2210 A, as seen in the figure below. The line has 3.32E-5 Ω resistance per meter and the bird's feet are 3.80 cm apart. What voltage does the bird feel? Homework Equations R=sigma(L)/A I=V/R The Attempt at a...
13. ### Short circuit problem

Homework Statement An underground telephone cable, consisting of a pair of wires, has suffered a short somewhere along its length (at point P in the Figure). The telephone cable is 4.00 km long, and in order to determine where the short is, a technician first measures the resistance between...
14. ### Electric field due to a finite line of charge

I get it. Thank you for your help.
15. ### Electric field due to a finite line of charge

I don't understand the difference between theta 1 and theta 2. Could you please explain to me on the graph?
16. ### Electric field due to a finite line of charge

Homework Statement A rod of length 25 cm has a uniform linear charge density of 7 μC/m. Determine the Electric Field at a point P located at a perpendicular distance 69 cm along a line of symmetry of the rod. Homework Equations E=k*charge density(integral(dx/(d^2+x^2)^3/2) The...
17. ### Time an object takes to oscillate

Homework Statement An object in SHM oscillates with a period of 5.73 s and an amplitude of 10.47 cm. How long does the object take to move from x=0 cm to x=5.78 cm? Homework Equations x=Acos(wt+ro) The Attempt at a Solution I solved for ro which was pi/2 when x=o and t=o. Then...
18. ### Time Constant problem

Homework Statement A spring with spring constant 18.39 N/m hangs from the ceiling. A 452 g ball is attached to the spring and allowed to come to rest. It is then pulled down 4.62 cm and released. What is the time constant if the ball’s amplitude has decreased to 2.85 cm after 32 oscillations...
19. ### Finding Phase Constant and air-track glider

Ok thank you very much for all your help. I greatly appreciate it.
20. ### Finding Phase Constant and air-track glider

The question has several parts and it's asking me for the phase at t=.5s. I used the same formula but it's wrong. Could you please let me know what's wrong? thank you.
21. ### Finding Phase Constant and air-track glider

I got the correct answer for the phase constant but I'm trying the phase for t=.5s. Sorry for the confusion.

23. ### Finding Phase Constant and air-track glider

ok, so for t=.5s I get -102.115 but that's wrong. All I did is wt+constant(-103.48). But that's wrong for some reason. Does the constant change at that time?
24. ### Finding Phase Constant and air-track glider

Oh sorry w=2.73. Sorry about that.
25. ### Finding Phase Constant and air-track glider

Also, in this case, is angular speed the same as velocity? If I wanted to find the phase at t=0 s would I just need to use wt+ro, w being the velocity?
26. ### Finding Phase Constant and air-track glider

is it because it's negative and the distance is negative?
27. ### Finding Phase Constant and air-track glider

yeah, I tried that as well which was 76.4751. Then I minus it from 180 so it's 103.525 but that's wrong.
28. ### Amplitude problem

Ok thank you very much for all your help I really appreciate it. I have one more question. Me and my friend have been trying to figure it out but we can't. Could you please help us. Thank you. https://www.physicsforums.com/showthread.php?t=320317
29. ### Amplitude problem

I got it. For some reason the answer was -.042 when the calculator was in radian. do you know why I have to put the calculator in radians? I have a test tomorrow and I would not have gotten this answer right.
30. ### Finding Phase Constant and air-track glider

I minus that by 180 so it's 107 but that's still wrong. What do you think is wrong?