Why, when you stroke a cat's fur, or comb your hair on a cold, dry day can you hear a crackling sound? Doing these things in a darkened room, you can actually see sparks. Explain.

Please explain to me! Thanx !!

Static electricity builds up with a positive charge on one of the objects and a negative charge on the other. The sparks in a dark room (it helps in VERY low humidity, also) are electrons (electricity) moving from the negative object to the positive object. You can see the same thing when sliding into a car on leather or fur seats on a cold dry day. In such a case I have been shocked when I place the metal key into the ignition socket of the car.

Thankyou soooo much!
-Aakriti

When you stroke a cat's fur or comb your hair on a cold, dry day, you can hear a crackling sound and sometimes see sparks in a darkened room. This phenomenon is due to static electricity.

Static electricity occurs when there is a buildup of electric charge on the surface of an object. In this case, as you stroke the cat's fur or comb your hair, friction between the two surfaces causes electrons to be transferred from one surface to the other. One surface becomes positively charged, while the other becomes negatively charged.

The crackling sound you hear is a result of the discharge of this built-up static electricity. When the charge becomes strong enough, it overcomes the insulating property of the air and jumps across the small gap between the surfaces, creating a tiny spark. In a darkened room, these sparks are visible as small flashes of light.

The visibility of the sparks is enhanced in very low humidity conditions because moisture in the air can help dissipate the electric charge more easily. On a cold, dry day, the air is often drier, and this allows the static electricity to accumulate more effectively.

It's worth noting that static electricity can also be experienced when sliding into a car on leather or fur seats. When you touch a metal key to insert it into the ignition socket, the charge can discharge through you, resulting in a quick electrical shock.

So, the crackling sound and sparks you observe when stroking a cat's fur or combing your hair on a cold, dry day are caused by the buildup and discharge of static electricity.