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Does the phrase "dip your lights" mean to turn them off or something else? Why is the word dip used?

Quote:

If you drive with your headlights on full beam in fog, the light will just reflect back on you. Dip your lights — it will be much easier to see.

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    I guess you do not drive. Cars have a "high" beam that points upwards/level and a "dipped" or low beam that points downwards, dipped downwards. Simple!
    – Fattie
    Jun 13, 2011 at 21:09
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    Perhaps it has been mentioned elsewhere in this long thread of comments below, but my grandfather had some old cars in storage, and some of them (in addition to having a hand crank in front to start them) had headlights which had hinges which allowed for manual adjustment. So dipping may have in fact been a term which stems from the physical act of getting out and pointing them down...
    – horatio
    Jun 14, 2011 at 16:34

2 Answers 2

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To be clear, the headlights of cars today usually have two filaments.

One filament projects the beam (off the mirrors behind) straight ahead (roughly level with the road, say).

The other one projects the beam (off the mirrors) downwards (ie dipped, pointing downwards).

Thus -- when the light is on normal (that is to say, "high" beam, because the beam is pointing up high), it hits the road a long way ahead.

In contrast, when you "dip" the lights, you will see the light shining on the road a fairly short distance ahead.

They are "dipped" ... pointing-low ... the beam is pointing downwards, rather than onwards.

The thing that you dip the lights with is called a "dip switch."

(Before the 60s they were a footswitch, now they are on a stalk, or obviously just automatic.)

Note that "dimming" the lights would not help, you would still dazzle the oncoming driver. You must, of course, point the beam downwards - it's how headlights work.

I mention "bulbs have two filaments.." in the early days of motoring there were different systems to point the headlights downwards, when a car was oncoming..

'Dipping' (low beam) [ie low, downwards onto the ground] headlamps were introduced in 1915 by the Guide Lamp Company, but the 1917 Cadillac system allowed the light to be dipped with a lever inside the car rather than requiring the driver to stop and get out..." etc etc.

Dipping headlights, one of the basic elements of driving, along with brakes, turning indicators, etc!

It would appear that using the word "dip" for dipping the headlights downwards, is now more BrE. It seems that in the USA, the word has transformed to "dim." Moreover, people in the USA tend to think of the downwards-dipped beam as the "normal" one, and you then have "brights", "high" beam, etc. Physically this is completely incorrect; dimming lights would achieve nothing, you have to literally point them downwards, i.e. dip them.

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    I've never actually hear the phrase "dip switch" used in this context; it's generally "headlight switch" or "dimmer" or some such. I'm not saying it's not correct, but - in general - if you hear the phrase "dip switch", the speaker is referring to a DIP switch, where DIP stands for dual-inline-package.
    – MT_Head
    Jun 13, 2011 at 21:52
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    @Joe You may want to note that on many vehicles, when the "high beams" are lit, they are lit in addition to the "low beams," thus earning them the commonly used title (in the US) of brights (as opposed to dims, which would indicate that only a single filament is lit). A simple Google search should show its prominent use. Furthermore, I question your assertion that the ability to drive and a technical comprehension of illumination technology are directly related.
    – snumpy
    Jun 13, 2011 at 22:08
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    @Joe Blow - 41, US, and I've driven for nearly 25 years. DIP switches have been used for persistent settings in small electronics items - mostly things with radios in them, like remote controls and especially for garage doors - since the early 80s at least, and I've known and used the phrase since I was quite small. As for the switch that dips the lights... in every car I've driven, the standard position is dipped, so that's the "high-beam" switch. People who drive with their high beams on all the time, blinding oncoming traffic, are dipsts**.
    – MT_Head
    Jun 13, 2011 at 22:09
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    @Joe... Finally, I would like to encourage you to be a little less scathing of fellow-users in your answers/comments.
    – snumpy
    Jun 13, 2011 at 22:09
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    @Joe - I think it may be a matter of where one lives. I live now in Los Angeles; I have to drive a very long way out of the city to find an open section of road - it's considered not just rude but slightly reckless to use high beams where they can dazzle oncoming drivers (or shine in the rear-view mirror of the car ahead.) Years ago, however, I lived in a very small town up in the mountains; the highway down to Sacramento was dark, deserted, and twisty, and you'd be a fool not to use your brights. You'd dim them (or dip them!), however, as soon as you saw oncoming traffic.
    – MT_Head
    Jun 14, 2011 at 6:43
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Generally, dipping the lights means reducing headlight intensity and turning off the ones that aren't angled toward the ground.

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    As a forty year old American motorist who learned to drive at age 12, I have NEVER heard this usage. I am wondering if I am an anomaly.
    – horatio
    Feb 10, 2011 at 16:06
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    @horatio: We use dim in America, while the rest of the English-speaking world, especially Britain, happily uses dip :)
    – Jimi Oke
    Feb 10, 2011 at 16:52
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    :) I see "Dip" signs everywhere ( highwaytrafficsupply.com/images/regulatory_signs.html/W15-9.jpg ) and I always wonder how they knew I was coming.
    – horatio
    Feb 10, 2011 at 17:08
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    FWIW I'll chime in as another American driver, driving for 33 years now, and have never heard the term "dip" when referring to headlights, while I've heard "dim" many, many times. Definitely not an American usage. Jun 14, 2011 at 6:44
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    "the crucial factor is the lowered angle of the headlight beams, not their brightness" - indeed. That's all there is to it.
    – Fattie
    Nov 21, 2017 at 23:04

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