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An LDR (light-dependent resistor) is a particular type of semiconductor (A material with a conduction rating in between that of a conductor and an insulator i.e. electricity flows through a semiconductor slower than through a conductor, but quicker than through an insulator).
Consider an atom as made up of just a nucleus with bound electrons. These electrons require varying amounts of energy to 'escape' from the atom. The semiconductor, as all known matter, is made up of atoms.
Light can currently be explained as being made up of packets of waves called photons where the frequency of these waves determines how much energy they are associated with (Energy = h * frequency: where h is a constant).
Therefore, if light associated with enough energy strikes the semiconductor, then the electrons requiring the equivalent energy to break the bonds will escape.
Electricity is concerned with a flow of electrons, therefore electrons escaping means there is an increase in electrical current.
This increased electrical current is equivalent to a drop in resistance and thus fluctuation in particular frequencies of light affects the resistance of the semiconductor.
What else can I help you with?
Why LDR used in PIR sensor?
industrial automaton
What is the type of ldr commonly used in schools?
automatic
What is an LDR symbol?
An LDR is a Light dependent resistor.
What is the meaning of LDR?
LDR refers to Light Dependent Resistor.
How does light affect LDR?
An LDR is a light dependent resistor, which is usually used to detect light levels, either ambient or reflected. The LDR works because incoming light carries energy, which can elevate the energy levels of electrons in a suitable medium to join the 'conduction band' which means that there are more charge carriers in the LDR, and hence the cell has lower resistance.
What happens to an LDR when a bright light is shined upon it?
As light intensity increases, resistance decreases, hence it will maximise current flow through the LDR. A LDR is a semiconductor, hence it does not give an Ohmic graph ( graph of V against I giving a constant gradient which represents a constant resistance) even if physical conditions such as light is kept constant. LDR's graph is non ohmic, ie it will give a decreasing gradient hence decreasing resistance when light increases.
What does LDR stand for?
Light Dependent Resistor LDR also means long distance relationship.
What is the symbol for LDR Holding Corporation in NASDAQ?
The symbol for LDR Holding Corporation in NASDAQ is: LDRH.
Which material is used in LDR?
Cadmium Sulphide (CdS), Cadmium Selenide (CdSe), Selenium, etc.
In what year did LDR Holding Corporation - LDRH - have its IPO?
LDR Holding Corporation (LDRH) had its IPO in 2013.
How and when can a LDR be used?
LDR could mean a long-distance relationship? It would be better to spell out abbreviations in full, as there could be several interpretations. More information is needed.
What does a LDR sense?
light
