and can be built using this IC due to which the IC is quite popular among electronic amateurs, experimenters and hobbyists. Although the IC is quite old but it is still popular. There are also improved versions of operational amplifiers available now days, which are also gaining popularity, like TL071.
The circuit is very simple and using only few external components. The sensitivity of the circuit can be adjusted with 150K variable resistor. The output current of the IC is 25mA due to which the relay cannot be operated directly with the IC therefore we have operated it through a 2N4401 NPN transistor.

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The figure below shows a project / schematic of LM741 light sensor relay switch circuit. The circuit is quite sensitive and will activate the relay when a small amount of light falls on the surface of the LDR.
LM741 is a well known operational amplifier IC. There are variety of electronic projects available

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LM741 Light Sensor Relay Switch Circuit