Quantum Phenomena

how would i do question 6a part 2?

how would i do question 6a part 2?

Remember about the emf of cells in parallel!Calculate the emf from A and B and then add them to C+D
This is a series arrangementThis will give total emf

We know the resistor rules, and that V = IR. Therefore, the same rule applied to emf (methinks)

where does this come from? how would you know that? is there a rule of some sort stating this?



i've managed to do it now though ^-^ thanks for the help

where does this come from? how would you know that? is there a rule of some sort stating this?

I just got taught it as being fact (part of my course)
The rule being as you add cells in parallel, the EMF they supply does not change overall, only the capacity changes.
This may not have been on your course

well ffs i never got taught this >.> well at least i know, so for example instead of just a 1.5 V emf cell there was a 2 V emf cell in parallel what would i count the total emf as now?

Ah now this is where its dangerous. To have two cells of different voltages in parallel is dangerous, as they will try and become the same voltage.

In your case, the 2V cell will actually discharge into the 1.5V cell to try and make them both the same voltage (1.75V in this case). This could potentially cause a massive malfunction, alot of heat will be created.

Anyway, supposing that they dont blow up you can use the equation $I=\frac{V_{1}-V_{2}}{R_{1}+R_{2}}$ where $V_1, V_2$ are the voltages of the cells and $R_1, R_2$ are the resistances of the cells.

Otherwise the total emf would be (if they are rechargeable, and they dont blow up) the average of the two emfs:
$V_{total}=\dfrac{V_1+V_2+ \cdots + V_n}{n}$

thanks so much ^-^