Why do the dash lights in my car (and the lights for the clock, radio, etc.) dim when I turn on my headlights?
You are right that the dash lighting dims when headlights are on in order to enhance night vision. But every car I’ve driven has had a way to adjust the brightness of the dash lighting, since it varies by personal preference and whether you are using the headlights during the day, at night on a lighted street or on an unlighted road. Until recently most cars had a relay switch that you pulled out about 2 inches to turn on the headlights, and the knob rotated to adjust the dash lighting. Today cars have rocker switches on the dash or a knob to twist on the turn signal. So they have a separate knob or wheel to adjust the dash lighting located somewhere on the dash, often down low and obscurely marked. Look around for it.
Some homes have light dimmers that are operated by rotation of a Knob. What is being changed in electric circuit when the knob is rotated?
Not an expert, this is speculation and a theory. As you rotate the dimmer you are likely influencing change on a variable resistor in the circuit, increasing or decreasing the resistance in the circuit. Essentially less current/voltage/energy is available for the bulb and therefore it is more dull.
Some homes have light dimmers that are operated by rotation of Knob. What is being changed in the electric circuit when the knob is rotated?
The device used is a variant of a THYRISTOR. What it does is it delays turning on the current for a portion of each cycle so that the mains volts are only applied in brief pulses. The wider the pulse then the more of the power is transmitted. The knob controls the width of the pulse. The reason that this is used is that it doesn't create heat. Unlike a resistor. I have designed and built these circuits for over 40 years to make realistic model train controllers with simulated mass. And they are used to control electric trams and trains.
Honda accord dashboard lights?
ive noticed on my '99 honda accord that at night, the dashboard lights are dim and I can hardly see them. How can I brighten the lights on the dashboard so I can see the various dials clearly.