The Reason Why Your Car’s Turn Signal Makes a Clicking Sound

Zmaj88, iStock / Getty Images Plus
Zmaj88, iStock / Getty Images Plus

The clicking of a turn signal ranks among the least-annoying sounds a car can make. Along with the flashing bulb behind the arrow in your car's dashboard, the gentle, rhythmic tick tick tick-ing tones are a sign that your blinker is working properly when you switch it on. Even as technology has progressed, this feature has remained a constant throughout generations of vehicles—or at least that's how it appears to drivers. According to Jalopnik, there's one thing that has changed, though: the actual source of that familiar sound.

The flashing turn signals began appearing in automobiles in the late 1930s when Buick made them standard in some models. Traditionally, the clicking sound is made via heat. Drivers would switch on their blinker, and the electricity would heat up a bimetallic spring in the car, causing it to bend until it made contact with a small strip of metal. When these two components connected, a current would pass through them and power the electric turn signal lights. The bimetallic spring quickly cooled down and returned to its original form, turning off the light, before the whole process started again to create a new flash. As the spring bent back and forth, it created a clicking sound.

The next evolution of turn signals used a similar trick, but instead of moving a spring due to heat, it sent the electronic pulse to an electromagnet via a chip. When activated, the electromagnet pulled up a metal armature and disconnected the current powering the light (or the opposite, depending on the relay setup). Without the pulse from the chip, the electromagnet turned off and the armature returned to old position and bridged the circuit providing power to the bulbs. As was the case with the thermal spring, the relay clicked every time it moved.

Up until recently, this was how most car turn signals functioned, but things have changed as cars have become more computerized. Many car manufactured today rely on computer commands to activate their turn signals, skipping processes that once produced the distinctive clicks. But the clicking sounds are something people grew up with, and drivers might be unsettled if they heard nothing after activating their blinkers. That's why the mechanical sound still exists in the computer era—even though in many modern cars, it's actually just being broadcast through the vehicle's audio system.

For a visual of how electronic flasher signal systems work in cars, check out the video below.

[h/t Jalopnik]

The Reason Dogs Twitch in Their Sleep

Tetiana Garkusha/iStock via Getty Images
Tetiana Garkusha/iStock via Getty Images

The sight of a dog batting its tiny paws around while sleeping is irrefutably adorable, and it’s not hard to imagine that your beloved pet is dreaming of swimming, fetching a Frisbee, or bounding around the yard in pursuit of a scampering squirrel.

In truth, that’s pretty much exactly what’s going on. Dogs, like humans, dream during the REM cycle of sleep, and their twitches are responses to whatever’s happening in those dreams. Though all dogs can exhibit muscle movements while dreaming, PetMD reports that it most often affects younger and older dogs. This is because of the pons, a part of the brainstem with two “off” switches that regulate movement during the sleep cycle.

“If either or both of these ‘off’ switches is not fully developed or has grown weak due to the aging process, then the muscles are not completely turned off and during dreaming, the animal will start to move,” Stanley Coren, a neuropsychological researcher and former psychology professor at the University of British Columbia, told PetMD. “How much movement occurs depends upon how effective or ineffective these ‘off’ switches are.”

As long as your dog looks like it’s having a grand old time in its dreams, you can sit back and enjoy the show. If you think your dog might be having a nightmare, be careful about waking it up. As the American Kennel Club (AKC) explains, a dog woken abruptly from a bad dream might bite you before it realizes its distress wasn’t real.

You should, however, learn to recognize the difference between a normal dream and a seizure.

“Some [dogs] manifest dreaming with twitching, paddling, or kicks of the legs. These movements are often brief (less than 30 seconds) and intermittent,” Jerry Klein, the AKC’s chief veterinary officer, described on the AKC website. “Seizing dogs’ limbs, on the other hand, tend to be rigid and stiffer, with more violent movement.”

The seizure can also be accompanied by loss of bowel control. If that description sounds familiar, you should talk to your veterinarian.

[h/t PetMD]

The Reason Doctors Have Such Sloppy Handwriting

Rostislav_Sedlacek/iStock via Getty Images
Rostislav_Sedlacek/iStock via Getty Images

It seems counterintuitive that doctors—widely regarded as some of the smartest, most detail-oriented people out there—so often have horrible handwriting. From a patient’s standpoint, it could seem downright terrifying. If your pharmacist misinterprets your trusted physician’s chicken scratch, you could wind up with a dangerously high dosage of medicine, or even the wrong medicine altogether.

In 2006, the National Academies of Science's Institute of Medicine estimated that doctors’ sloppy handwriting was killing more than 7000 people per year, and preventable medication errors were harming around 1.5 million Americans annually. Many medical offices have since switched to electronic medical records and prescriptions, and some states have even required them to do so.

But that doesn’t tell us why doctors’ penmanship is so poor in the first place. One reason is because doctors have to write much more than we realize.

“In the medical field, if it’s not documented, it didn’t happen,” Celine Thum, medical director at ParaDocs Worldwide, told The Healthy.

If you’re the very first patient of the day, the record of your visit and any prescription slips you get might be perfectly legible. Ten hours and dozens of appointments later, however, your doctor’s hand muscles are probably pretty cramped.

The content they’re writing isn’t particularly easy to spell, either. If a doctor is jotting down glomerulonephritis, for example, they may not stop to make sure all those vowels are in the right places.

“We have so many technical terms that are impossible to write,” Thum said. “You sometimes scribble to cover the error.”

However, if a prescription looks indecipherable to you, it’s possible that your doctor is using shorthand that your pharmacist will immediately understand—like the abbreviation QD, from the Latin phrase for “one a day.”

If you’re confused about what the doctor has written on your prescription slip, you can always ask them to clarify aloud, and double-check that it matches what’s printed on your prescription bottle.

[h/t MSN]

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