Recent content by erinec

1. Circuit with an uncharged capacitor - desperate

If there is no R2, then the battery charges the capacitor. Btw, that raises another question. Since electrons are the charge carriers and electrons cannot ever travel to positive side of the capacitor, does the resistor 1 connected to the positive plate of the capacitor play a role? I am so...
2. Beta Decay not a specific problem, just a question

I understand that a beta plus decay emits positron and beta minus decay emits electron. For the calculation of kinetic energy of the particle released, you take into account the mass of electron for beta plus, but why is it that you DON'T take into account the mass of electron for beta minus? I...
3. Circuit with an uncharged capacitor - desperate

circuit with an uncharged capacitor -- desperate Homework Statement http://img91.imageshack.us/img91/7533/physicsimage.gif [Broken] Switch S has been open for a long time. It is closed suddenly at t=0. A long time later, it is opened. Determine the potential across and the current through each...
4. Strength of magnetic field at a point

Homework Statement http://img291.imageshack.us/img291/9572/picture2ehv.png [Broken] What is the strength of the magnetic field at point P? The answer is 7.9×10^−5 T. However, I used the equation B = u*I/(2*pi*d) and keep getting 5*10^-5 T. Homework Equations B = u*I / (2*pi*d)...
5. What determines the brightness of bulbs?

Homework Statement This is not a specific problem, but I am wondering, what exactly determines the brightness of identical bulbs? The current going through it? The voltage? Something else? Thanks. Homework Equations N/A The Attempt at a Solution N/A
6. Induced Current question

Which radius should I use? The distance from the wire to the the inner side of the loop or the outer side of the loop?
7. Induced Current question

Well... the problem is that.. I got this far: emf = | d(flux)/dt | = dB * A / dt = dB (0.04*0.01) / dt = dB (4*10^-4) / dt but i do not know how to get dB...; in other words, i am totally lost. I have B(r) = u0I/(2*pi*r) This is my first time seeing this type of question.. and I am very...
8. Induced Current question

Homework Statement The rectangular loop shown has resistance 20.0 mΩ. Determine the induced current in the loop at the instant shown. Answer: 66.7µA http://img264.imageshack.us/img264/7386/picture1nlz.png [Broken] Homework Equations induced emf = |d(flux)/dt| I = emf / R...
9. Magnetic field and capacitor

Homework Statement A 10-turn coil of wire having a diameter of 1.0 cm and a resistance of 200m Ω is placed in a 1.0 mT magnetic field. The coil is connected to an uncharged 1.0µF capacitor. The coil is quickly pulled out of the magnetic field. Determine the total charge which...
10. Electric Potential (Potential Energy)

Ah thanks I got the correct answer now.
11. Electric Potential (Potential Energy)

Thanks for the reply! May I ask what formula you are using to solve for the distance?
12. Electric Potential Energy

Homework Statement A proton and an alpha-particle are fired directly toward each other from far away each with an initial speed of 0.01c. Determine their distance of closest approach measured between their centres. Homework Equations See below. The Attempt at a Solution What I did...
13. Electric Potential (Potential Energy)

Yes I used consistent units. And still not getting the answer. I do not know what I am missing.
14. Electric Potential (Potential Energy)

Homework Statement A proton is fired from far away towards a Hg nuclide. Determine the distance of closest approach of the proton to the centre of the nuclide when the initial speed of the proton is 4.0 * 107 m/s. (Answer: 13.8 fm) Homework Equations (1/2)mv2 = kqq/r The Attempt at a...
15. Speed of a proton at triumf

Homework Statement Determine the speed of a proton whose kinetic energy is 500 MeV. The mass of a proton is 938.27 MeV/c2. Homework Equations K = (1/2)mv2?? The Attempt at a Solution The correct answer is supposed to be 0.758c, where c is the speed of light. Of course, I plugged...