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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.
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Anonymous
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If you have a 12point6V battery and a 9V receiver how can you work out which resistor is needed?
you better not. you need a 9V regulator for this, not a resistor!
Can a 6 volt adapter be substituted for a 9 volt adapter?
No, of course not. The 6v adapter only produces 6v, while the load expects 9v.
What is 9 volts across a 300 ohm resistor?
9v
What is the resistor of 18 ohms when connected to a 9v battery?
Even though it is connected to a 9 volt source, it is still a resistor.
In a simple series circuit where you have a 9V supply connected to a negative terminal with about 2 amps of current flowing you have a resistor of 100 ohms in between the 9V supply and 0V?
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.
Can you use a 9v 300mA adapter on a 9v 200mA device?
No. The adaptor will overheat.
A 9v battery is in a series with a 100 resistor and there is a current of 0.09 a flowing through the circuit what is used by the circuit?
0.81 APEX
Will a 9v DC adapter damage a device that requires a 6v DC adapter?
Yes, the manufacturer specifies what the working voltage of a device will be and that voltage has to be adhered to.
What size of resistor is required to operate the LED from a 9V battery?
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.
Can you use 9V 500mA adapter for 9v 700mA 6.3VA device?
yes, if the other adapter is a va
If the current running through a wire is 1.2 amperes and it passed through a resistor of 7.5 Ohms what is the voltage of the system?
9V by using ohms law
Can you use a 6V 2amp adapter on a 6V 600mA device?
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.
