You can only use a resistor to drop a voltage at a constant current. If you know the current, use Ohm's law to calculate the resistor value.
3phm
you better not. you need a 9V regulator for this, not a resistor!
No, of course not. The 6v adapter only produces 6v, while the load expects 9v.
9v
Even though it is connected to a 9 volt source, it is still a resistor.
If a 9V supply is connected to a 100-ohm resistor, then the current is not 2 Amps,or even close to it.I = E/R = 9/100 = 0.09 amp.
No. The adaptor will overheat.
0.81 APEX
Yes, the manufacturer specifies what the working voltage of a device will be and that voltage has to be adhered to.
In order to determine what size of resistor is required to operate an LED from a 9V battery, first start by knowing the current and voltage required for the LED. That information is available in the LED's specifications. For discussion purposes, lets assume a typical LED at 2.5V and 50mW. The translates to a forward current of 20mA. Build a simple series circuit containing a 9V battery, a resistor of an as yet unknown value, and the LED. By Kirchoff's current law, the current in the LED is the same as the current in the resistor, which is also the same as the current in the battery. This is 20ma. By Kirchoff's voltage law, the voltage across the LED plus the voltage across the resistor equals the voltage across the battery. This is 6.5V. (9 - 2.5) By Ohm's law, resistance is voltage divided by current, so the resistor is 6.5 / 0.02, or 325 Ohms. The nearest standard value to that is 330 Ohms. Cross check the power through the resistor. Power is voltage times current, or 6.5V times 0.02A, or 0.13W. A half watt resistor is more than adequate for this job.
yes, if the other adapter is a va
9V by using ohms law
No. You need to use the exact battery charger for the battery specified by the manufacturer, in order to achieve the correct charge cutoff point. In particular NiCad and similar batteries detect full charge by detecting the knee point in voltage per unit time given a specific charge current. Using the wrong charger could result in overcharge which will damage the battery.