Image Caption 1: The compounded helix structure (called a coiled coil) of the tungsten (symbol W, Z=74) filament of a 200-watt incandescent light bulb.
Features:
Most of the output energy comes out in the infrared band (fiducial range 0.7 μm -- 0.1 cm) and dissipates into heat energy in the surroundings (i.e., into waste heat).
Explication:
R = (2πaL)/(4πr**2) cylinder to sphere surface area ratio where "a" is cylinder radius, L is cylinder length, and r is sphere radius. πa**2*L = (4π/3)*r**3 equating cylinder volume to sphere volume to solve sphere radius. r = [(3/4)*a**2*L]**(1/3) sphere radius r. R = (1/2)*(4/3)**(2/3)*[aL/(a**2*L)**(2/3)] cylinder to sphere surface area ratio with r eliminated. R = (1/2)*(16/9)**(1/3)*(L/a)**(1/3) simplied cylinder to sphere surface area ratio. R = (2/9)**(1/3)*(L/a)**(1/3) exact formula. R = (0.6057 ...)(L/a)**(1/3) exact formula with decimal fraction coefficient .