physic notes


Electrical faults are dangerous because they can cause electric shocks and fires. 


*Never touch a mains appliance(or plug and socket) with wet hands.never touch a bare wire or a terminal at a potential of more than 30V. 


*Check cables, plugs and sockets for damage regularly ,check smoke alarms and finally infrared sensors regularly. 


  *when choosing an electrical appliance, the power and efficiency rating of the appliance need to be considered. 


*filament bulbs and halogen bulbs are much has efficient than low energy bulbs 


*A filament blub is very inefficient the energy from the hot bulb gradually makes the plastic parts of the bulb socket brittle and they crack. 


*Low energy bulb are much more efficient so they don’t become hot like filament bulbs do.different types of low energy bulb are now available. 


 *low energy compact fluorescent bulbs (cfls) are now used for room lighting instead of filament bulbs. 


 *Low energy light emitting diodes(ledc)used for spotlight are usually referred to as high power ledcs.They operate at low voltage and low power.They are more efficient than filament bulbs or halogen bulbs and they last much longer. 


*Rutherford used the measurements from alpha scattering experiments to prove that an atom has located s a small positively charged central nucleus where most of the mass of the atom is located.  


*The plum pudding model could not explain why some alpha particles were scattered through large angles. 


*The nuclear model of the atom correctly explained why the alpha particles are scattered and why some are scattered through large angles. 


*Isotopes of an element are atoms with the same number of protons but different numbers of neutrons, therefore they have the


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