# Why does the light in a room come on instantly when you flip a switch several meters away?

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Why does the light in a room come on almost instantly when you flip a switch several meters away? Electrons travel at the speed of light through the wire. … Starting the flow of electrons from the switch into the wire almost immediately causes electrons to flow from the other end of the wire into the lightbulb.

## Why then does a light turn on instantly when you turn it on?

If you make one electron move when you turn on a switch, the electrons throughout the wire move, even if the wire is miles long. Therefore when you turn on a switch, the electrons in the light start moving “instantly” as far as we are concerned, i.e. something starts to happen throughout the electrical system.

## Why does a light bulb light up immediately?

Since the repulsion that causes this push is carried by electromagnetic waves, the effect of the circuit being closed travels down the wire at close to the speed of light, and the bulb lights up almost instantly!

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## Why does an electric bulb light up when one moves the switch?

In a conductor there are large number of free electrons. … The current which is set up does not wait for the electrons flow from one end of the conductor to the another end. It is due to this reason, the electric bulb glows immediately when switch is on.

## What happened to the light bulb when the switch was off what does it indicate?

Answer: When the switch is ON the bulb and resistor are “shorted” and the neon bulb does not glow. When the switch is OFF the neon bulb and resistor are still in-circuit across the (open) switch contacts.

## How fast does a light turn on?

Speed of Light (c):

Light travels at a constant speed of 1,079,252,848.8 (1.07 billion) km per hour. That works out to 299,792,458 m/s, or about 670,616,629 mph (miles per hour).

## Why does electricity travel at the speed of light?

In the case of an electrical cord connecting a table lamp or some other household item to a power source, the copper wire inside the cord acts as the conductor. This energy travels as electromagnetic waves at about the speed of light, which is 670,616,629 miles per hour,1 or 300 million meters per second.

## What indicates that the bulb light up?

When a light bulb connects to an electrical power supply, an electrical current flows from one metal contact to the other. As the current travels through the wires and the filament, the filament heats up to the point where it begins to emit photons, which are small packets of visible light.

## Does the bulb light up?

Both the metal casing and tip of the bulb are connected to the circuit, forming a closed circuit. Thus, electricity is able to flow through the wires in the circuit to the filament, allowing the bulb to light up. … Thus, electricity is unable to flow through the filament, preventing the bulb from lighting up.

## At what pressure will the light bulb light up?

Most modern bulbs are filled with an inert gas to reduce evaporation of the filament and prevent its oxidation. The gas is at a pressure of about 70 kPa (0.7 atm).

## How does electricity flow from a battery to a light bulb?

With the circuit closed, electrons can flow, pushed from the negative terminal of the battery through the lightbulb, to the positive terminal. … Those charges nearest the light bulb will take one step through the circuit and start transforming energy from electrical to light (or heat).

## How do electrons move in a wire?

When a negative charge is brought near one end of a conductor electrons are repelled. … When electric voltage is applied, an electric field within the metal triggers the movement of the electrons, making them shift from one end to another end of the conductor. Electrons will move toward the positive side.

## Where do photons go when you turn off the light?

So when you turn off the light switch, the light doesn’t go anywhere, the current just stops flowing, which means that there is nothing to give the atoms energy so that they can transition between different energy levels.

## Where does the dark go when you turn on the light?

When you light a lamp, the photons from the lamp bounce all over the room, and hence the darkness “disappears”, so to speak. Absence of light doesn’t exist when there is presence of light.

## Why do light bulbs glow after turning them off?

The filament of an incandescent bulb gets extremely hot to give off white-hot light. When you turn off the power to the bulb, the filament takes a few seconds to start cooling down. So it continues to glow slightly as the filament is still quite hot for a few seconds.