Electricity has to pass through the filament which, when it gets hot enough from resistance to the current, begins to glow and give off light.
a person
circuit
It takes a # 194 mini bulb.
The switch is not needed.
Eight people are more than enough to change a light bulb. Usually one person is needed.
It was dark and they needed a supply of light to read books and do other things
A light bulb is manufactured to operate on a specific voltage. The voltage can be a low as needed and the manufacturer will compute the size of the filament that is needed for a specific wattage. If you are referring to a threshold voltage then that is another question that needs to be asked.
Michael Faraday's made a light bulb with a platinum wire, he put it in a small glass globe, and attached it to a low voltage source. it glowed and produced light. Platinum is expensive. It only worked at low voltage. Others made lightbulbs. Edison decided a light bulb was a good idea but it needed to be made inexpensively. It needed to work at a higher voltage. The source of the electricity needed to be different from the place where the light bulb would be used. He looked for a material that could be made inexpensively and could last. It needed to be able to take higher voltage. He heated some thread until it turned to carbon. Then he made a vacuum inside a light bulb. He put the thread inside the bulb. It worked. He created a light bulb. It could be made inexpensively. It could work at a fairly high voltage.
New bulb needed or broken wire
batteries, wire, connectors, and light bulbs
3157 bulb
194 LED
They both are needed to run a lamp or a light bulb.