How long does a light last?

Answer 1

The phrase "How long does a light last?" can have multiple interpretations depending on what you're referring to:

1. **Light Bulb Lifespan:** If you're asking about the lifespan of a light bulb, it depends on the type of bulb and how often it's used. Traditional incandescent light bulbs tend to last around 1,000 to 2,000 hours, while more energy-efficient options like compact fluorescent lamps (CFLs) can last around 8,000 to 10,000 hours. LED (light-emitting diode) bulbs are known for their longevity and can last anywhere from 20,000 to 50,000 hours or more.

2. **Speed of Light:** If you're referring to the speed of light, which is approximately 299,792,458 meters per second (about 186,282 miles per second), it's a constant value in the vacuum of space. Light travels at this speed, and it takes about 8 minutes and 20 seconds for light from the Sun to reach Earth.

3. **Duration of Light Emission:** If you're asking about how long a light source emits light, that depends on the source itself. For example, a flashlight emits light as long as its batteries have energy. The light emission can be instant, continuous, or time-limited based on the technology and design of the light source.

Please clarify your question if you're referring to a specific aspect of light.

Answer 2

Light will continue until it is obstructed or absorbed. Light is obstructed when it strikes a solid, opaque object such as a planet, or an asteroid. Light is absorbed (not a great word for what actually happens) when it falls into a gravity well such as one caused by a singularity or black hole.

Answer 3

A light year is not a unit of time, it is a unit of distance. It is the distance light travels in one year in a vacuum.