This main components used in this circuit are Light dependent Resistor(LDR), NE555, and an LED.
The principle in this circuit is when the light from tubelight falls on the LDR resistance of LDR is very less and +Vcc is appeared at the second pin of 555 which is operated in monostable mode. So as +Vcc appears at pin 2 then the output of the 555 is zero (Why output is zero? for more information about 555 see this link). When tubelight is switched off light does not fall on the LDR so LDR offers high resistance so now at pin 2 it is grounded , so the output is one (in terms of Boolean).Note that this circuit is kept near tubelight where more light is falling on it and also more light due to daylight in the morning.
Output:When light is not falling on the LDR i.e.,LED is glowed .
Output of NI My Daq when light is not falling on the LDR.
Output:When light is falling on LDR.(LED is not glowing)
Output of NI My Daq during light is falling on LDR.