Physics : D.C circuits

anpanman SG

1.I have a question on finding the current flowing through each branch of a parallel circuit. Is it possible to find the current flowing through each branch using proportion method when you have the value of the total current flowing through and the resistance of each component? I tried using this method, but it doesn't seem to work.

Does it work(using proportion method) if you want to find resistance when you have info. on the current flowing through and also the potential difference of whole circuit? Or is it simply that you CÄN'T use proportion method at all?

2. In both parallel and series circuit, does having a higher voltage mean that that particular component in each circuit is brighter?

If for example you have 2 resistors of the same resistance in both parallel and series circuit, which circuit will have the more brightly lit bulbs? (Just a query)

Yea, these are all the doubts I have in my mind. Do help in wherever way possible. Having Physics Practice exam tomorrow, in real need of help. Thanks.

dkcx SG

2. In both parallel and series circuit, does having a higher voltage mean that that particular component in each circuit is brighter?

If for example you have 2 resistors of the same resistance in both parallel and series circuit, which circuit will have the more brightly lit bulbs? (Just a query)

Yea, these are all the doubts I have in my mind. Do help in wherever way possible. Having Physics Practice exam tomorrow, in real need of help. Thanks.

Its the current that affects the brightness if i didn't remember wrongly, voltage is just a 'carrier'.

sbs8104h SG

2. In both parallel and series circuit, does having a higher voltage mean that that particular component in each circuit is brighter?

If for example you have 2 resistors of the same resistance in both parallel and series circuit, which circuit will have the more brightly lit bulbs? (Just a query)

Yea, these are all the doubts I have in my mind. Do help in wherever way possible. Having Physics Practice exam tomorrow, in real need of help. Thanks.

i can't really understand point 1 but for 2, it appeared in my test paper recently

For series Circuit> The light bulbs will be dimmer as they have to share the voltage together.

For parallel Circuit> Both light bulbs will light at the same brightness as they are evenly split. I always remember that my physics teacher always repeating this point

eagle SG

i can't really understand point 1 but for 2, it appeared in my test paper recently

For series Circuit> The light bulbs will be dimmer as they have to share the voltage together.

For parallel Circuit> Both light bulbs will light at the same brightness as they are evenly split. I always remember that my physics teacher always repeating this point

It is the power that affect the brightness, not just current. Think energy ;)

In this case, we use V^2/R, where V is the voltage and R is the resistance of the bulb. We don't use I (current) in the calculations because it varies with V and R according to V = IR and it is harder to calculate...

In any case, in the series circuit, the current remains constant throughout. In the parallel circuit, the current in a path depends on the voltage divided by the resistance. Hence, for a parallel circuit, you will calculate that more current is being drawn from the battery.

eagle SG

You can use, but in an inverse way. But it is harder when we work with parallel circuits of 3 branches and above.

Instead of doing that, take it as voltage is constant in all the branches, and I = V/R, to calculate. It will reduce confusion a lot.

The proportion method for series circuit also stems from I = V/R anyway

sbs8104h SG

It is the power that affect the brightness, not just current. Think energy ;)

oh yar..i forgotten that part

dkcx SG

It is the power that affect the brightness, not just current. Think energy ;)

Ok, my physics sucks :p Just kept thinking that its current that kills and voltage is more just a carrier of it cos large voltage with low current is alot less deadly than high current low voltage.

eagle SG

Ok, my physics sucks :p Just kept thinking that its current that kills and voltage is more just a carrier of it cos large voltage with low current is alot less deadly than high current low voltage.

actually both are equally deadly

crimson soldier SG

actually both are equally deadly

Voltage is actually the first cause right?

When a high voltage is applied to your body, a conducting path will be established through your body to the ground point. Then current = voltage / resistance of body =p

eagle SG

You can be at high voltage, but if no conducting path is established, then nothing will happen to you, other than all your hairs will stand out due to electro statics ;)

Mr.ms.chairperson SG

Ans: As eagle says, proportional method works. But it is an inverse proportion method. Let's say total current is 6A and it is split into two paralle branches, with resistance at the top branch to be y and the resistance at the bottom to be 2y (where y is any arbitiary number). I'm assuming this is the question you got without information on the voltage. What you just need to remember is that the voltage is the same in both branches in parallel circuit. Recall V=IR.

Let's compare both the branches. The bottom branch has 2 times the resistance as compared to the top branch. Since V is the same, therefore it follows that the current in the bottom branch(i.e z) should be half the current as in the top branch(i.e 2z).

If you're still confused,

Top branch

V=IR=2z*y=2zy

Bottom branch

V=IR=z*2y=2zy