If the 3 ohm resistor is in parallel to the 12 ohm (I can't see it in the image) then the current through it is 12V/3ohm = 4A Amps are Coulombs/s The charge on the electron is 1.6e-19C So 4 amps means 4/1.6e-19 = 2.5e19 electrons/s.
The reciprocal of this gives the number of electrons per second:
1/2.5e19 = 4e-20 s/(elect. charge)
The power in the 3 ohm resistor is 12*4=48W. This is Joules/sec. We know it takes on average 4e-20 s to get one electron charge through the resistor so we multiply: 48W * 4e-20s = 1.9e-18J
Note: In reality there are many electrons moving through the resistor together, and a single electron does not move this fast, but the total energy to do it would be equivalent to this.
Type of conductors determines rate of flow of current
With the switch open, there's no current in the circuit, and therefore
no voltage drop across any of the dissipative elements (the resistor
or the battery's internal impedance). So the entire battery voltage
appears across the switch, and the voltmeter reads 12.0V .
<h2>
a) Displacement of penny = 1300 i + 2400 j - 640 k</h2><h2>b) Magnitude of his displacement = 2729.47 m</h2>
Explanation:
a) He walks 1300 m east, 2400 m north, and then drops the penny from a cliff 640 m high.
1300 m east = 1300 i
2400 m north = 2400 j
Drops the penny from a cliff 640 m high = -640 k
Displacement of penny = 1300 i + 2400 j - 640 k
b) Displacement of man for return trip = -1300 i - 2400 j
Magnitude of his displacement = 2729.47 m
