Static electricity, magnetism and electromagnetic induction (11,12,13) Flashcards
When does static electricity occur?
When electric charges (when electrons)are transferred onto or off the surface of an insulator
When do insulators become negatively charged?
when electrons move onto the insulator (polythene) from another object from friction (cloth). Because they are gaining electrons
When do insulators become positively charged?
When electrons move off the insulator (acetate) onto the cloth . Because they are losing electrons.
How does earthing happen?
When a charge is built up and then electrons are transferred back into the earth to get rid of the charge.
How do lightning strikes happen?
1) water particles (or ice) in clouds gain electrons from other particles by friction as they rub against each other
2) the cloud gains electrons and an overall negative charge
3) electrons in the ground are repelled by the cloud
5) lightning jumps as electrons to get rid of the charge
What is electrostatic induction?
for example when a negatively charged balloon touches a neutral wall, the positive charges in the wall get attracted to the balloon and they attract as the balloon has induced a charge on the wall.
What direction does the electric field point in a positive charge?
What charge does an electric field have if it is point inwards?
What is an induced magnet?
A magnet like an electro magnet which can be turned off
What is the name of the type of magnet which cant be turned of and is always magnetic?
What four metals are magnetic?
Steel, iron, nickel and colbalt
What is Flemings left hand rule?
Used to find either the direction of the field, direction of current or direction of the force. (usually in the context of a motor)
Field: First Finger
Current: seCond finger
What is a solenoid?
A wire in a coil which can create a strong magnetic field when charged.
What is Flemings right hand grip rule?
Used to find either the direction of current or field around a wire
Your thumb points in the direction of the current.
Your fingers curl in fist in direction the field.
What is the motor effect?
A simple electric motor can be built using a coil of wire that is free to rotate between two opposite magnetic poles. When an electric current flows through the coil, the coil experiences a force and moves. This is called the motor effect. The force is always strongest when the wire is perpendicular to the direction of the magnetic field.