Meaning & use
light beam
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Meanings
nouncountable
A narrow stream of light that travels in one direction from a source such as a lamp, the sun, or a laser.
Grammar: A countable compound: one light beam, two light beams.
Patterns
- a light beam from something
- a light beam through something
A thin light beam cut through the dusty air of the attic.
The lighthouse sends a powerful light beam across the water.
Scientists pointed a light beam at the mirror to measure the angle.
nouncountabletechnical
A beam of light used by a device as a signal or sensor, such as in a security alarm, garage door, or barcode scanner.
Grammar: Often described as being broken or interrupted when the sensor reacts: break the light beam.
Patterns
- break the light beam
- interrupt the light beam
The garage door stops if anything breaks the light beam.
A hidden light beam triggers the alarm when someone walks by.
The scanner reads each label with a red light beam.
Word forms
| plural | light beams |
|---|
Common combinations
- narrow light beam
- A narrow light beam shone through the keyhole.
- break the light beam
- If you break the light beam, the doors open.
- focused light beam
- A focused light beam can cut through metal.
- direct a light beam
- He directed a light beam toward the far wall.
- bend a light beam
- A glass prism can bend a light beam.
- sweeping light beam
- A sweeping light beam swept over the harbor every ten seconds.
Synonyms and how they differ
- ray
- A ray is a single thin line of light, often used for sunlight, while light beam is a slightly wider shaft.
- shaft of light
- A shaft of light is a descriptive phrase for light seen through a gap, such as a window, with a more poetic feel.
- beam
- Beam alone means the same thing, but light beam makes clear you mean light and not, say, a wooden beam.
- searchlight
- A searchlight is the device that sends out a powerful beam, not the beam itself.
Opposites
Word family
Commonly confused: light beam or light year? light beam or headlight?
light beam vs light year
A light year measures distance, not light itself, and is how far light travels in a year.
light beam vs headlight
A headlight is the lamp on a vehicle, while a light beam is the stream of light the lamp produces.
Practice
A garage door stops when something interrupts the invisible ___ across the doorway.
Choose one answer.
A light beam is a narrow stream of light that a sensor can detect being interrupted. A switch, bulb, or fixture are physical objects, not something an object can break by walking through.
Make it your own
Write a sentence using “light beam”, then check it and compare it with the examples above.