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Static and charge - OCR GatewayElectric charge

Electric current is caused by moving electric charges. The effects of charge and electric fields can be investigated by looking at the forces they exert on conductors and insulators.

Part of Physics (Single Science)Electricity

Electric charge

All matter has , in the same way that all matter has mass. have no overall charge - they are neutral. This is because atoms contain equal numbers of protons and electrons. carry a negative and carry a positive electric charge.

Learn more on static charge in this podcast

Static

Electrons can be made to move from one object to another. However, protons do not move because they are tightly bound in the of atoms.

For example, when a plastic rod is rubbed with a duster, electrons are from one material to the other. The material that gains electrons becomes negatively charged. The material that loses electrons becomes positively charged.

Image gallerySkip image gallerySlide 1 of 3, A plastic rod is covered in negative charges (electrons). It is adjacent to a duster covered in positive charges., The duster picks up electrons from the rod. This leaves the rod with a positive overall charge and the duster with a negative overall charge.

Static charge occurs when electrons build up on an object. Static charge:

  • can only build up on objects which are , eg plastic or wood
  • cannot build up on objects that act as , eg metals

Conductors allow the electrons to flow away, forming an .

When a static charge on an object is discharged, an electric current flows through the air. This can cause sparks. Lightning is an example of a large amount of static charge being discharged.