what speed does the speedometer show when you travel on the bike.explain in two sentences
Answers
Answer:
Explanation:
Here's what we want out of our speedometer. We have the car's wheels rotating at a certain speed and we want to know, with a simple pointer and dial, what that speed is. So we need to connect the spinning wheels to the pointer in some clever fashion. Even that is pretty tricky: the wheels are racing around but the pointer, some distance away, merely flicks back and forth. How do we convert continuous, spinning motion into intermittent, flickery, pointer motion? The answer is to use electromagnetism!
The shaft that turns the car's wheels is connected to the speedometer by a long, flexible cable made of twisted wires. The cable is a bit like a mini driveshaft: if one end of the cable rotates, so does the other—even though the cable is long and bendy. At the top end, the cable feeds into the back of the speedometer. When it rotates, it turns a magnet inside the speedometer case at the same speed. The magnet rotates inside a hollow metal cup, known as the speed cup, which is also free to rotate, though restrained by a fine coil of wire known as a hairspring. However, the magnet and the speed cup are not connected together: they're separated by air. The speed cup is attached to the pHow does it all work? As the speedometer cable rotates, it turns the magnet at the same speed. The spinning magnet creates a fluctuating magnetic field inside the speed cup and, by the laws of electromagnetism, that means electric currents flow inside the cup as well. In effect, the speed cup turns into a kind of electricity generator. But, unlike in a proper generator (the kind that makes electricity for your home in a power plant), the currents in the speed cup have nowhere to go: there's nothing to carry their power away. So the currents just swim about uselessly in swirling eddies—we call them eddy currents for that very reason. Since they're electric currents, and they're moving in an electrical conductor inside a magnetic field, another law of electromagnetism says they will create motion. How? The currents actually make the speed-cup rotate in such a way that it tries to catch up with the spinning magnet. But the hairspring stops the cup from rotating very far so it just turns a little bit instead, pulling the pointer up the dial as it does so. The faster the car goes, the faster the cable turns, the quicker the magnet spins, the bigger the eddy currents it generates, the greater the force on the speed cup, and the more it's able to pull the pointer up the dial. If you can't picture all that clearly, take a look at the little animation below.ointer that moves up and down the speedometer dial.