Constructing a Home-Made Single Stage Coilgun

[Decarabia]

Hi

I have some doubts regarding the construction of a home-made single stage coilgun, I'm using a plastic tube(the way the object will travle through),an iron sphere(the object to be accelerated), and 8 cylindrical iron coils distributed equally on the end of the tube.

• The tube has 2 inchs of diamater and 1m in length
• the iron cylinders have 10 cm in length and half inch of diameter
• the sphere has 1 inch of diameter

This is my science fair project,and i wanted to know if it can work,if you guys need an image or don't understand something, i can post images or explain better on the thread.
Oh, my energy source has 12 volts and an unknown value of electrical current, AC.
The copper wire I'm using on the coils have 1mm of diameter.

thanks

 

[kuruman]

If I understand your proposed set up correctly, you have 8 cylindrical coils arranged symmetrically at one end of a meter-long plastic tube. You propose to put a 1"-dia. steel ball (about 2.5 ounces) at the other end, energize the coils with a 12-V source of AC and expect the ball to accelerate presumably attracted by the coils. You are correct in having doubts. Here are two big reasons why it will not work.
1. The magnetic force drops (in the best of circumstances) as $1/r^3$ with distance $r$. This means one meter away, the force is 8,000 times smaller than its value at 2" (5 cm.) How strong a permanent magnet do you need to attract the ball at 2 inches? Your coil arrangement needs to be 8,000 times stronger.
2. Why is the current AC? Why do you think electromagnets are connected to DC power supplies? Even if the magnetic field were strong enough to attract the sphere, it will have to switch direction every 120th of a second (assuming 60 Hz AC) How far do you think the ball will move in that time before the force acting on it switches direction?

Sounds like a Wile Y Coyote setup to me.