Hi, just wondering how LDRs work- I don't understand how if the resistance decreases as the light intensity increases it switches on at night- surely the resistance would be too high and it should turn on in the day??

Aform of energy that is reflected or emitted from objects in the form of electrical and magnetic waves that can travel through space. there are many forms of  electromagnetic  energy including gamma rays, x rays, ultraviolet radiation, visible light, infrared radiation, microwaves and radio waves.