Question

A 15 V constant voltage battery is connected to 120 kΩ resistor. A 15 V constant voltage battery is connected to 120 kΩ resistor. 1) What is the current in the resistor in [mA]?Multiple Choice question2) How many electrons pass through the resistor each second?a) 7.8x1014 electronsb) 1.25x10-4 electronsc) 1.6x10-19 electrons

Answer 1

We will have the following:

1)

`I=(V)/(R)\Rightarrow I=(15V)/(120000\Omega)\Rightarrow I=1.25\cdot10^(-4)A`
`\Rightarrow I=0.125mA`

2)

First we determine the quantity of coulombs:

`Q=(1.25\cdot10^(-4)A)(1s)\Rightarrow Q=1.25\cdot10^(-4)C`

Now, we know that 1 coulomb represents 6.24*10^18 electrons, so:

`1.25\cdot10^(-4)C\cdot\frac{6.24\cdot10^(18)\text{electrons}}{1C}=7.8\cdot10^(14)\text{electrons}`

So, approximately 7.8*10^14 electrons pass each second.