Perhaps you are asking about the eternal light? Synagogues have an eternal light in front of or above the ark, the ornate cabinet holding the scrolls of the Torah used for public reading during worship services. The light is a symbol of God's presence and a symbol of the eternal light that used to burn in front of the Holy of Holies in the Temple in Jerusalem back before the Roman Empire destroyed that and made off with the lampstand (you can see the image of that booty on the Arch of Titus in Rome).
The ner tamid, or eternal light, is a reminder of the lamp in the Beis Hamikdash that never went out.
There is no standard item positioned behind the eternal light in a synagogue. It depends on the decor of the synagogue, and not on Jewish law.
transmitted light is required for the purpose of examining internal features of gemstone inclusion.
need and purpose of internal mobility
The "eternal light" in the synagogue is not a permanent yahrtzeit light - it is a sign of the eternal covenant between G-d and the Jews.
the ark, eternal light and other
The filament is a special metal composition of tungsten that conducts current and heats up and emits light as a result of the current and its internal resistance.
No, but it is customary where possible, for synagogues to have windows.
The local board of directors or council of a synagogue interviews the cantor according to their own internal policies.
The chief purpose is prayer. Services are held every day. In addition, many synagogues have Torah-classes, free of charge; and some have the occasional social function. Congregating in the synagogue also serves to strengthen community and interpersonal ties.
It is when somebody does something on purpose.
The planet light is its internal heat.