whats the difference between a charged plastic rod and tha attraction for a small peice of paper and that of a magnet and how it attracts a small piece of iron?
A magnet is a material or object that produces a magnetic field. A low-tech means to detect a magnetic field is to scatter iron filings and observe their pattern, as in the accompanying figure. A hard or permanent magnet is one that stays magnetized, such as a magnet used to hold notes on a refrigerator door. Permanent magnets occur naturally in some rocks, particularly lodestone, but are now more commonly manufactured. A soft or impermanent magnet is one that loses its memory of previous magnetizations. Soft magnetic materials are often used in electromagnets to enhance (often hundreds or thousands of times) the magnetic field of a wire that carries an electrical current and is wrapped around the magnet; the field of the soft magnet increases with the current. Magnetic field lines of a solenoid which are similar to a bar magnet as illustrated above with the iron filingsTwo measures of a material's magnetic properties are its magnetic moment and its magnetization. A material without a permanent magnetic moment can, in the presence of magnetic fields, be attracted (paramagnetic), or repelled (diamagnetic). Liquid oxygen is paramagnetic; graphite is diamagnetic. Paramagnets tend to intensify the magnetic field in their vicinity, whereas diamagnets tend to weaken it. Soft magnets, which are strongly attracted to magnetic fields, can be thought of as strongly paramagnetic; superconductors, which are strongly repelled by magnetic fields, can be thought of as strongly diamagnetic. Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. Electrically charged matter is influenced by, and produces, electromagnetic fields. The interaction between a moving charge and an electromagnetic field is the source of the electromagnetic force, which is one of the four fundamental forces.
One force is static electricity - different charges on the plastic rod and the paper attract each other and the other force is ferromagnetism - the pull of a magnetic field on certain metals, particularly iron.
My doctor said that I couldn't lift more than 50 lbs. Although I try not to lift more than my 2 yr old and he's around 27 lbs. Talk to your doctor to be on the safe side. But if's it's your job and your body is already used to it, I'd think it would be fine.
geez i sure hope so! im 18 weeks pregnant and im carrying my 1 year old all the time and i plan to keep doing so. As long as you are healthy and everything is going ok, im am sure its ok.lots of woman do it.
20 pounds is the limit during your entire pregnancy. This is what my OB has told me 3 times. My pregnancy books say it depends on your physical aspects, so it might vary by height weight.
