Question 1

I've heard the terms "in series" and "in parallel", can someone help me understand the difference between the two and what they mean?

Accepted Answer

In simplest terms series means only one path for current to travel on, and parallel means more than one path for current to travel on.

Question 2

what is difference between resistance and resistivity?

Accepted Answer

_In simple, you could understood resistance by using a simple analogy, which would also lead to understand the Law of Resistivity and the Unit of Resistivity. So, Suppose you are moving through a narrow path, and a lot of guys are coming on the opposite direction, which is letting you to slow down. But, Imagine if the path was too wide you would easily go through them. But, If its too long, the rush of people will slow you down along with a lot of Distance. Similar, in a movement of Charges through a wire :-
You are the Charge, which is moving by the potential difference created by the batter. But, there are some bad guys who are resisting you to slow down(these guys can also be good sometime) which is resistance. And, if you somehow manage to squeeze through them, it would take time but, if the path was wider, you could easily move in a fast speed.
There fore, we have reached the Equation,_
```
 Resistance = Potential Difference / Current
R = V/I
```
*Scientifically Resistance is the opposition that a substance offers to the flow of electric current. The standard unit of resistance is the ohm, sometimes written out as a word, and sometimes symbolized by the uppercase Greek letter omega (Ω).  When an electric current of one ampere passes through a component across which a potential difference (voltage) of one volt exists, then the resistance of that component is one ohm*.
 _And as i have said above, through a long path, you would have to go slowly, since there are along way to travel and so many guys to conquer, but if the way was wider, its pretty easier to escape fast_
```
 So, we have reached our second equation, 
Resistance is directly proportional to Length of wire and inversely proportional to the area of cross section.
R ∝ l/a
So, we use a constant of proportionality ρ (Which is unit of Resistivity) to  remove the proportionality sign so, R = ρ * l/a
So, ρ = R*a/l = Ω* m^2 / m => Ωm
So, Si  unit of resistivity is Ωm.
```
*Scientifically , its a measure of the resisting power of a specified material to the flow of an electric current*.

Question 3

So connecting the battery has a larger affect than connecting the electromagnet?

Accepted Answer

The battery was still connected, there was just an additional load (the electromagnet) added to the circuit. The wires were partially not shown in the video, but if you follow the connections assuming that each wire completes the circuit, it makes more sense.

Physics library

Course: Physics library > Unit 18

Series load

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