Glia that provide myelin for neurons in the brain are called
schwann cells
oligodendrocytes
microglia
astrocytes

oligodendrocytes

Explanation:

Glial cells are part of the nervous system. These are helper cells that support the function of the central nervous system (CNS) and can be called oligodendrocytes when they supply myelin to neurons.  These cells are responsible for producing the myelin sheath have the function of electrical insulator for CNS neurons. They have extensions that wrap around the axons, producing the myelin sheath.

It is estimated that there are 10 glia cells in the CNS for each neuron, but because of their small size, they occupy half the volume of nervous tissue. They differ in form and function and they are: oligodendrocytes, astrocytes, Schwann cells, ependymal cells, and microglia.

answer; both surfaces of the membrane are nonpermeable

measuring light intensity

light meters can be used to measure light intensity. the meter is held at the soil surface and pointed in the direction of the maximum light intensity, and then the meter is read.

errors can be made when measuring light intensity by accidentally shading the light meter. the reliability of the results can be checked by taking many samples.