<prompt> All are true about light curing composites except:Intensity of LED is more than QTH lightConventional composite can be used in deep cavitiesPlasma arc light can be used in deeper area for better curingNone  <response>: Light activation in visible light curing ranges between 460 and 470 nm wavelength. On activation, photoinitiator camphorquinone combines with amine accelerator and releases free radicals which start the polymerization. Different types of lights used in curing are:Tungsten-quartz halogen QTH curing unitPlasma arc curing PAC unitLight emitting diode LED unitArgon laser curing unitTungsten-quartz halogen QTH curing unit is conventional and most commonly used curing light for composite resins. It is an incandescent lamp, which uses visible light in the wavelength in the range of 410 to 500 nm and intensity of 400-900 mWcm2.Plasma Arc Curing has a high-frequency electrical field, which is generated using high voltage. This field ionizes the xenon gas into a mixture of ions, electrons and molecules, thereby releasing energy in the form of plasma. Hence, it is applicable for usage in deeper areas cause of the high-intensity light more than 1800 mWcm2 curing cycle in 6 to 9 seconds.Light Emitting Diode unit usually have a long life and emits powerful blue light. This light falls in a narrow wavelength range of 455 nm to 486 nm. This corresponds to the range of camphorquinone photoinitiator found in most of the composite resins.Argon laser light has a wavelength of 470 nm, which is monochromatic in nature. It produces intensity of 200 to 300 mW.Ref: Textbook of Operative Dentistry, Nisha and Amit Garg, 3rd edition Chapter:17 