What Is Par Wattage?

What Is Par Wattage? ‘PAR’ directly indicates how much light energy is available for plants to use in photosynthesis. … A 400 watt HPS lamp has less PAR, typically 120 to 128 watts, but because the light is yellow it is rated at higher lumens (for the human eye). “Illumination” for plants can be measured

What Year Did The Flashlight Come Out?

What Year Did The Flashlight Come Out? Hubert experimented with everything from electric tie tacks to electric flower-pots before acquiring the patent for this first Eveready flashlight in 1898. Hubert’s first portable flashlights were hand-made from crude paper and fiber tubes, with a bulb and a rough brass reflector. Did they have flashlights in 1917?