List of devices

A rotor is a machine part that rotates. On a car, a wheel is attached to a rotor which makes the car roll.

Scales are a device used for measuring how heavy something is. There are many different types of scales. Originally scales were made to balance like a seesaw, and you put the thing you wanted weighed on one side and weights on the other side until it balanced out.
Today, scales are often digital and need batteries to work. There are scales you stand on so you know how much you weigh, kitchen scales like in the picture so you can weigh food, and really big industrial scales to weigh trucks full of grain so it can be sold by weight.

A sconce light fixture attached to a wall. In the past, sconces held candles or oil lamps. Modern electric sconces may be designed in an old fashioned style like the one in the photo, or they may be sleek and modern.

A sewing machine is a device, usually powered by an electric motor, that can sew much neater and straighter than you can by hand. Modern sewing machines have lots of different stitches built into them. Some sewing machines can even connect to a computer and stitch very intricate embroidery from pictures on the computer automatically.

A speaker, or loudspeaker, is a device that converts electrical signals into sound. They do this by using that electrical signal to vibrate a cone-shaped device at particular frequencies that are encoded by the signal, which produces sound. Larger cones are better at making low sounds, smaller ones are better at making high sounds.

A spool is a cylinder-shaped object that you wrap something around. Most spools are used to store thread or cables.

extension A spring is a flexible device that stores energy when it is stretched, squeezed, or bent. It is often made from strong metal wire wound into a coil. When the force is removed, the spring tries to return to its original shape. This movement can serve purposes like keeping something steady, making a pen click, or making a toy bounce.

A stethoscope is a device that doctors and nurses use to listen to sounds inside you. Stethoscopes are most often used to listen to your heart beat, or listen to you breathe.

extension A stopwatch is a special type of watch that counts the passing of time rather than telling you what time it is. It has buttons to start, stop, and zero the count. It is used to time races and competitions.

A subwoofer is type of speaker that produces very low sounds, called bass. It is usually larger than other speakers. and may have a large cone that moves back and forth. Subwoofers make deep sounds such as drum beats, explosions, and the rumble of an engine easier to hear and feel. They are usually used in conjunction with other speakers that handle the higher sounds.