In a 9V circuit, all the resistors are 20 or 40 kilo Ohms.
Convention says that calcs should therefore be quoted to 1 sig fig, since the volts are the least accuracy.
2 seems better though. Any ideas?
In a circuit where all the resistors have values of either 20 or 40 kilo Ohms, the convention for quoting calculations is to round the final answer to one significant figure. This convention is followed because the accuracy of the voltage (9V) is considered to be the least accurate component in this scenario.
However, using a single significant figure may result in a loss of precision in the final answer. Rounding to two significant figures can provide slightly more accuracy. The choice of whether to use one or two significant figures ultimately depends on the level of precision required for your specific application or analysis.
To calculate the total resistance in this circuit, you need to consider the different possible combinations of resistors. Since you mentioned using either 20 or 40 kilo Ohm resistors, the combinations can be:
1) Two 20 kilo Ohm resistors in series: The total resistance is obtained by simply adding the individual resistances. Therefore, the total resistance would be 20 + 20 = 40 kilo Ohms.
2) Two 40 kilo Ohm resistors in series: Again, the total resistance is obtained by adding the individual resistances, resulting in 40 + 40 = 80 kilo Ohms.
3) One 20 kilo Ohm and one 40 kilo Ohm resistors in series: Similar to the previous cases, the total resistance is determined by adding the resistances. In this case, the total resistance would be 20 + 40 = 60 kilo Ohms.
Keep in mind that these calculations assume the resistors are connected in series. If they are connected in parallel, the calculations would be different.
So, to summarize, the convention suggests rounding calculations to one significant figure due to the least accurate component, which is the voltage. However, using two significant figures may provide slightly more accuracy. The specific choice of the number of significant figures depends on the desired level of precision for your application.