# physics alevel edexcel circuit question

someone explain y the picture, y does the power supply not act in the middle, doesnt this mean stopclock wont start when circuit is broken off.

I am confused about the black dot also, does this mean anything?
and for the cgp book it shows the batter in the middle (as i understand) but not black dot.

Is the power supply different from a batter?
(edited 1 year ago)
this is what im pointing to
Original post by Username1_2_3
this is what im pointing to

@mqb2766
someone explain the picture, y does the power supply not act in the middle, doesnt this mean stopclock wont start when circuit is broken off.

I am confused about the black dot also, does this mean anything? apparently this means parallel or is it just a black dot
and for the cgp book it shows the battery in the middle (as i understand) but not a black dot.

Is power supply different from a battery?
(edited 1 year ago)
Original post by Username1_2_3
@mqb2766

The black dot circled is simply a node / junction. Sometimes its omitted from the circuit diagram if its obvious the lines are connected.

Edit - however, once the switch is flipped and the ball is released, there isnt any power for the stopclock which I guess is an oversight when the person created the diagram.
(edited 1 year ago)
Original post by mqb2766
The black dot circled is simply a node / junction. Sometimes its omitted from the circuit diagram if its obvious the lines are connected.

thanks so ill just ignore black dots, but what about the power supply, should this not be where i placced the 2 lines, as when the switch is flipped how does the lower circuit receive any energy
Original post by Username1_2_3
thanks so ill just ignore black dots, but what about the power supply, should this not be where i placced the 2 lines, as when the switch is flipped how does the lower circuit receive any energy

I was editing the post when you replied. That is wrong. Where does the diagram come from?

The circuit diagram
https://spark.iop.org/measurement-g-using-electronic-timer
here is less pretty but at least the clock has power.
(edited 1 year ago)
Original post by mqb2766
I was editing the post when you replied. That is wrong. Where does the diagram come from?

The circuit diagram
https://spark.iop.org/measurement-g-using-electronic-timer
here is less pretty but at least the clock has power.

thanks, so we're right and the literal physics textbook for alevel edexcel physics in wrong
just to verifiy, bateries and power supplies are practically the same thing?

Original post by Username1_2_3
thanks so ill just ignore black dots, but what about the power supply, should this not be where i placced the 2 lines, as when the switch is flipped how does the lower circuit receive any energy
Original post by Username1_2_3
just to verifiy, bateries and power supplies are practically the same thing?

Cant see any reason to prefer one or the other here, but generally a battery would be dc
Original post by mqb2766
Cant see any reason to prefer one or the other here, but generally a battery would be dc

does direct current even matter when it comes to circuits, i never understand it
Original post by Username1_2_3
does direct current even matter when it comes to circuits, i never understand it

I would have thought they meant a battery when they drew the diagram so a dc power source.
Original post by mqb2766
I would have thought they meant a battery when they drew the diagram so a dc power source.

so a battery mean dc power, but what does that change about the circuit, current just goes both ways?
Original post by Username1_2_3
so a battery mean dc power, but what does that change about the circuit, current just goes both ways?

https://www.power-and-beyond.com/whats-the-difference-between-ac-and-dc-power-a-0c5c48e598b5e1266e6cebc5731227c2/
Nothing would change for this circuit

I dnt understand how were supposed to understand which way is is positive and which way is negative for alternating current, Is it just assumed top to bottom of power supply is positive and bottom to top is negative?
(edited 1 year ago)
Original post by Username1_2_3

I dnt understand how were supposed to understand which way is is positive and which way is negative for alternating current, Is it just assumed top to bottom is positive and bottom to top is negative?

@mqb2766
sorry ur the only person that helps, feel free to ignore me if u want