PHYSICS ELECTRICITY YR9

Useful Equations

}Q = It

}V = IR

}E = QV

}P = E / t

}P = IV

Static Electricity

When two objects are rubbed together, they exert friction force and electrons are transferred from one to the other. This works best with insulators as they retain the static charge when the rubbing stops. Like charges repel and opposite charges attract. Charged objects are attracted to neutral ones for example a negative balloon will be attracted to the wall as the electrons in the atoms of the wall are pushed further from the electrons in the balloon leaving no shielding between the protons in the wall and the negative charge. Electric field lines go from positive to negative. A charged object can be grounded by connecting it to earth

Charging by Induction

1. A charged object for example a positive rod is brought close to a neutral object for     example a ball and the free electrons in the ball move towards the rod

2. A wire is connected to the ground and free electrons are drawn out of the ground towards the positive charge.

3. The wire is removed THEN the rod and because there are more electrons than protons in     the ball 

Dangers of static electricity

When refuelling an aircraft,…