Circuit
Light bulb
Ra
battery
Rb
LDR
Circuit concept
The circuit senses the ambience of light and
depending on the presence/absence of
sufficient ambience light. it turns the bulb on/off
automatically The bulb gets on when there is
insufficient ambience, and switches off when
enough ambience is present
This circuit does its job automatically without
manual operation
LDR
Light dependent resistor
A resistor that act upon light exposure. The circuit
symbol is box with a circle . When light falls on
the LDR, the resistance, hence the voltage
coming across it is decreasing.
How it works
During daytime, when light falls on LDR,the
resistance of LDR decreases.the decrement of
resistance causes more potential to the other
resistor .the potential of across LDR is directly
transmitted , because of the low potential
difference, across base and emitter, one of them
goes cutoff restricting any flow of current from
collector to emitter, turning the lightbulb