Long weekends are the best! But now it’s Monday night and I have to do all of my homework… I didn’t take much pics this weekend so I thought about what I’d blog as I was getting ready for dinner. Then suddenly, as I sat down, a light went off both in and above my head! My sister had turned on the light above our dining table—reminding me of variable resistors and light dimmers. The light switch for that particular light is a circular knob that you push to turn on/off and turn to adjust the brightness; however there are light dimmer switches can also be used by sliding a lever. In the case of my light, a simple method was devised to adjust light levels: variable resistors. A typical resistor is made of a material that doesn't conduct electrical current well. A variable resistor is made from a resistive material comprised of a stationary and a moving contact arm. In the second picture, I captured the knob and drew its basic components (sorry it's messy..i drew it in on my camera). The total resistance of the resistor in this case is varied by adjusting the distance the current has to flow through the resistive material. In my illustration, the moving contact arm is touching the bottom right portion of the resistor. By turning the knob to the left, the contact arm moves in the counter-clockwise direction; thus decreasing the distance the charge has to travel. So when this occurs, the contact arm is to the left and the charge only has to travel through a small amount of resistive material—brighter light! Similarly, when the contact arm is in a position similar to the one I drew, the light emitted is dimmer because the charge has to move through more resistive material. Physics is so illuminating!
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