Conductors and Insulators. In a conductor, electric current can flow freely, in an insulator it cannot. Metals such as copper typify conductors, while most non-metallic solids are said to be good insulators, having extremely high resistance to the flow of charge through them.onductors and Insulators. In a conductor, electric current can flow freely, in an insulator it cannot. Metals such as copper typify conductors, while most non-metallic solids are said to be good insulators, having extremely high resistance to the flow of charge through them.
Butterhead lettuce. A type of head lettuce whose botanical name is Lactuca sativa var. heirloom. Two common types are Boston and bibb lettuce. Have small, round, loosely formed heads with soft, buttery-textured leaves ranging from pale green on the outer leaves to pale yellow-green on the inner leaves.
Figure 1. Hydroponic Lettuce. Lettuce (see Figure 2) is a plant that has quite a small root system and is therefore particularly suited to being grown in water culture, or using the nutrient film technique (NFT).See the hydroponics systems page on this site for more information about these types of gardens.igure 1. Hydroponic Lettuce. Lettuce (see Figure 2) is a plant that has quite a small root system and is therefore particularly suited to being grown in water culture, or using the nutrient film technique (NFT).