Electrons will flow against the electric field lines because their charge is negative, and the electric field thus exerts a force $\mathbf{F}=q\mathbf{E}$ on them which is in the opposite direction. Thus electric field lines inside the wire go from the positive to the negative terminal and the electron flow goes from the negative to the positive terminal. Electric current goes, consistently with both of the above (because the electron charge is negative), from the positive to the negative terminal.
The electric field lines will twist with the conductor if you bend it into some weird shape. (This is due to slight charge buildups on the wire bends and is beautifully explained by Purcell.) For the situation you describe, the electric field lines and the wire pretty much match already so just draw some more lines. You've already explained current flow in terms of electrostatics in a circuit like this! the only snag is what the state of affairs is inside the battery, but that's another story.
- If electrons are really drifting from one point to another point, how will they drift at the contact? Will they drift from copper edge to aluminium edge?
They will drift from one rod to the other just as they would if both rods were of the same material. The DC voltage source that you apply across the outer end-face of one and the outer end-face of the other rod sets up a high potential at one end-face and a low potential at the other end-face.
Charge will then drift from higher to lower potential.
A potential is just a fancy word for their tendency to move. Pack many electrons at one end and they will really want to move away from this spot due to their mutual electric repulsion force. If they could, then they would very much like to move to the other end where the repulsion is much lower.
- (Electric) potential energy $U$ is a word invented for this tendency for them to want to move somewhere else if they can. We say that the point of higher electric potential energy is the point they want to move away from. Just as gravitational potential energy is higher, when the ball is on the shelf than when it is on the ground - the ball wants to fall downwards, if allowed, and that is what the potential energy describes.
- (Electric) potential $V$ is the same, but per charge $V=U/q$. This is often easier for comparing different points.
- Voltage is a word for (electric) potential difference $\Delta V=V_2-V_1=U_2/q-U_1/q$ (sometimes denoted $V$).
That you have two rods of two different materials doesn't change the fact that the charges want to move from one end to the other. Those rods may introduce different resistances as well as a contact resistance (maybe so high that no current is able to flow), but the tendency will still always be from that same end to the other.
- I have read that electrons actually don't move from one place to another, they'll just travel a very small distance, during their travel they'll pass charge from one electron to another.
Well, electrons do move, but not much. That is correct.
An electron is always in constant violent motion and bumping into to atoms around it all the time. This is just random motion. Overall, on average, it doesn't move anywhere. When a potential difference is established, the electron suddenly feels a tendency towards one direction. It still moves around randomly and violently, but it at the same time slowly drifts sideways. And this is what creates you current - the drift speed.
The drift speed is usually small - something like a few millimeters per second. But think of a company of soldiers. When the Lieutenant yells "March!", they all start at the same time. The first soldier doesn't get fast to the end - but the signal does reach the end right away.
This is a simplification of course, and it may be more fruitful for you to think of the electrons as a line of stones or billiard balls. When you strike the first one, it hits the next which hits the next etc. And that "hitting" propagates very, very fast to the end stone or ball, much faster than the first one moves. The same with electrons, and the propagation of their electrical force from the first to the proceeding ones is almost at the speed of light.
Also I have read that electrons vibrate at their position and their energy will transfer from one place to another (dominoes analogy). Which is true among these?
The vibration idea is mainly useful for AC circuits. The domino analogy is still useful for both DC and AC, but don't think of electrons as "vibrating" in DC; it is better to think of them as drifting. (In AC cases you also have drifting - just drifting that quickly changes direction all the time, and therefore the idea of vibrating).
- How do electrons flow inside the conductor? Please post any pictures so that I can understand clearly.
The above explanation of the violent random motion of electrons should due. Search on Google for this and you'll get illustrations that visualize it.
- If we touch a high voltage positive terminal, do we definitely get an electric shock? Given that positive terminal attracts electrons, will electrons in my body get attracted to voltage? How do electrons behave in this situation?
When touching a high-voltage positive terminal, the mobile charges in your body (not just electrons, but also ionic compounds and alike) will move slightly, but they will quickly even out your potential. Yes, you can get an electric shock, similar to when you rub your feet over a carpet and collect a net charge on your body. That gives your body a higher potential than your surroundings, and therefor you may feel an electric shock (and maybe even see a spark), when touching something conductive that can move all your excess charge away rapidly.
But that will quickly be over with. Your body will in an instant reach the same potential as what you are touching. Exactly how dangerous it is to touch a high-voltage cable and feel this effect, is not something I can answer directly.
Best Answer
Your teacher's description is not bad. The phrase about mutual pushing is vague. I'm not sure if he or she means there is pushing to get things started, or pushing to maintain current, or something else. I think it might be fair to say that mutual pushing establishes the charge distribution needed to maintain the current, which I'm about to describe.
Your picture is pretty good, too. Once the current is established, charges accumulate on the surface of the wire in such a way that the surface charge density is positive near the positive battery terminal, negative near the negative battery terminal, and passes through zero somewhere in the middle. The result of this gradient of surface charge is to induce a uniform electric field inside the wire, much as you have drawn. It's this field that applies force to the charge carriers in the wire. You might argue that the charge carriers will accelerate without bound (Newton's second law), but no, each carrier will eventually collide with an impurity or defect and stop (or deflect, or turn back) the carrier, thus limiting the speed. A thermal vibration can do the same. Higher resistance materials have more impurities and defects, and thus lower average carrier speed. Raising the temperature of the material increases the number of thermal vibrations and also raises the resistance. This effect is prominent in a light bulb.