CIE A Level Physics復習筆記22.1.5 The Work Function
Photoelectric Emission The work function Φ, or threshold energy, of a material is defined as: The minimum energy required to release a photoelectron from the surface of a material Consider the elec...
Photoelectric Emission The work function Φ, or threshold energy, of a material is defined as: The minimum energy required to release a photoelectron from the surface of a material Consider the elec...
Threshold Frequency & Wavelength The concept of a threshold frequency is required in order to explain why a low frequency source, such as a filament lamp, was unable to liberate any electrons i...
The Photoelectric Effect: Basics The?photoelectric effect?is the phenomena in which electrons are emitted from the surface of a metal?upon the absorption of electromagnetic radiation Electrons remo...
The Electronvolt The electronvolt is a unit which is commonly used to express very small energies This is because quantum energies tend to be much smaller than 1 Joule The electronvolt is derived f...
The Particle Nature of Light In classical wave theory, electromagnetic (EM) radiation is assumed to behave as a wave This is demonstrated by the fact EM radiation exhibits phenomena such as?diffrac...
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Smoothing In?rectification, to produce a steady?direct current? or voltage from an?alternating current??or voltage, a?smoothing capacitor?is necessary Smoothing is defined as: The reduction in the ...
Rectification Graphs Rectification is defined as: The process of converting?alternating current??and voltage into?direct current??and voltage Rectification is used in electronic equipment which req...
Mean Power In mains electricity, current and voltage are varying all the time This also means the?power?varies constantly, recall the equations for power: Where: I =?direct?? current (A) V =?direct...
Root-Mean-Square Current & Voltage Root-mean-square (r.m.s) values of current, or voltage, are a useful way of?comparing?a.c current, or voltage, to its equivalent direct current, or voltage Th...
Properties of Alternating Current & Voltage An alternating current (a.c) is defined as: A current which periodically varies from positive to negative and changes its magnitude continuously with...
Faraday's & Lenz's Laws Faraday’s law tells us the magnitude of the induced e.m.f in?electromagnetic induction?and is defined as: The magnitude of the induced e.m.f is directly proportional to ...
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