jekch85
11-20-2006, 11:56 PM
1) An electrons 'falls' toward a proton from far away. If it started with zero velocity, how fast is it moving when it gets to a typical atomic distance of 1.0x10^-10 m from the proton?
a) 3.2x10^6 m/s
b) 2.2x10^6 m/s
c) 1.6x10^6 m/s
d) 1.1x10^6 m/s
I used the conservation of energy, PE=KE, which gives charge(q)*electric field potential(V)=0.5*m*v^2. Then, V=k*q/radius(r), so the equation would become k*q^2/r^2=0.5*m*v^2. From this equation, I got the answer 2.2x10^6 m/s, choice b. Is my equation correct, or should I be using something else?
2) The Earth's magnetic field above the Earth's equator is about 10^-4 T northward. If a proton is initially moving upward at 5x10^5 m/s, it will
a) curve east, making a circle with r=50m
b) curve west, making a circle with r=50m
c) curve east, making a circle with r=3 cm
d) curve west, making a circle with r=3 cm
e) keep moving in a straight path
For this question, I got answer a using the equation radius(r)=m*v/q*B(magnetic field). I'm pretty sure that part is right, but what I don't know is which way it will move. I think I'm confusing myself with the right hand rule. Any suggestions would be awesome.
3) I have a 500-turn circular coil of wire, 0.10 m in diameter, in a 0.025 T magnetic field. Initially the plane of the coil is perpendicular to B. If I flip the coil 180 degrees in 1/30 of a second, what is the average voltage created across the ends of the coil?
a) -6.0V
b) -12V
c) -3.0V
d)-24V
I got c for this one. I used found the flux to be 1.96x10^-4 and then I found V by using V=-number of turns(N)*(flux)/time. I got -2.94, but is this the right way to solve this type of problem?
Thank you to anyone who can help me!!!!
a) 3.2x10^6 m/s
b) 2.2x10^6 m/s
c) 1.6x10^6 m/s
d) 1.1x10^6 m/s
I used the conservation of energy, PE=KE, which gives charge(q)*electric field potential(V)=0.5*m*v^2. Then, V=k*q/radius(r), so the equation would become k*q^2/r^2=0.5*m*v^2. From this equation, I got the answer 2.2x10^6 m/s, choice b. Is my equation correct, or should I be using something else?
2) The Earth's magnetic field above the Earth's equator is about 10^-4 T northward. If a proton is initially moving upward at 5x10^5 m/s, it will
a) curve east, making a circle with r=50m
b) curve west, making a circle with r=50m
c) curve east, making a circle with r=3 cm
d) curve west, making a circle with r=3 cm
e) keep moving in a straight path
For this question, I got answer a using the equation radius(r)=m*v/q*B(magnetic field). I'm pretty sure that part is right, but what I don't know is which way it will move. I think I'm confusing myself with the right hand rule. Any suggestions would be awesome.
3) I have a 500-turn circular coil of wire, 0.10 m in diameter, in a 0.025 T magnetic field. Initially the plane of the coil is perpendicular to B. If I flip the coil 180 degrees in 1/30 of a second, what is the average voltage created across the ends of the coil?
a) -6.0V
b) -12V
c) -3.0V
d)-24V
I got c for this one. I used found the flux to be 1.96x10^-4 and then I found V by using V=-number of turns(N)*(flux)/time. I got -2.94, but is this the right way to solve this type of problem?
Thank you to anyone who can help me!!!!