00:01
All right? so in this question given us that assume 285 amp current is flow through a copper wire and electrons travel through a copper wire with cross -sectional area 0 .17 square and the length of copper wire is 0 .43 meter and the question says that the number of charge carrier per unit volume is 8 .49 multiplied 10 to the power 28 meter cubic in a here n represented the number of charge carrier per unit volume.
00:31
And here in this question, the question says that how long does it attack electrons to get from a car battery to the starting battery? that means the question says that in how much time electrons get from car battery to starting motor.
00:47
So here we need to find the time in which electrons travel from car battery to starting motor.
00:53
So first of all students we already know that i is equal to n .e.
00:57
A vd here i represented electric current and here represent the number of charge carrier per unit volume and e here represent charge on one electron a here represent cross -sectional area and vd here represent drift velocity and if you already know that velocity is equal to displacement divided by time so here what is the displacement here? displacement is the length of the length of copper wire okay and length of copper wire is given 0 .43 that will so we can write that drift velocity is equal to displacement and the displacement is length of power by that means l divided by time and assume that electrons take time t take time t to transfer from car battery to starting motor so here displacement l divided by time t so here we need to find the value of this time okay, so from here we already we can write that i is equal to an and e, a, vd and the value of vd, that means drift velocity is length divided by time.
02:07
So from here we can, in order to find the value of time t, we can write t is equal to an ea, l divided by i...