You are given a task to desigs a moion senso esed on LDR. As aiwill sound whvem

Question

You are given a task to desigs a moion senso esed on LDR. As aiwill sound whvem a band(motion) is placed in front of LDR a) Explain how the LDR operases 14 pts) b) How would you characterize LDR using a DMM (assume LOR is placed is s daris qu LDR values with and without hand motion inthe kiloohmstobeuod is design- c) The comparator circuit of Fig. 4% is used to condition the LDR sensor signal Vs The turner sounds when the output goes high with hand heet ofthe sensor. The comprar outpa peshgh when Vs exceeds the threshold Vth. Seleet the approperiane setcr location in the cicuit Rs or Re an des n the circuit (set appropriate R values) based on your LDR measurement aboe, 115 pol R. 45 LDR d) Discuss all possible effects (envirnmental VB .) o the sysim operaton?5 pes

Explanation / Answer

Answer:-a) An Light Dependent Resistor(LDR) is a passive component which has a variable resistance value. The resistance of LDR varies as per the intensity of light falling on LDR. This is also known as photo-resistor.

LDR is mainly made from semiconductors. These semiconductors can gain photons in presence of light and from energy of photon electrons in semiconductor jump into conduction band which causes increment in current and hence decrement in resistance. In darkness LDR provides very high resistance value.

b) When we connect a Digital Multimeter(DMM) across the LDR in dark, we find a very high resistance value on DMM. When light falls on LDR the resistance value decreases suddenly.

c) The figure element in circuit is not visible clearly. Kindly explain in comments about the components.

d) For the LDR, dust particles, humidity can affect the working of LDR as these things prevents the light to reach on LDR semiconductor. Also at high temeperature the working of LDR may change.

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