Measuring resistance in a simple circuit

[dttom]

I would like to ask two questions...

the first one is about rheostat, which its resistance could be changed. R=V/I, when R increases, three cases are possible, V increases while I keeps constant; I decreases while V keeps constant; and V increases while I decreases at the same time, which of them is the case?

 

http://hk.pg.photos.yahoo.com/ph/loiyalunait/detail?.dir=798fscd&.dnm=3d31scd.jpg&.src=ph

 

the experimental set up shown in the above diagram is used to find out the relationship between resistance, voltage and current. when a current pass through the rheostat current and voltage decreases as the rheostat consumes enery, the current then flow through the other resistor and the current after the passage is recorded, however, as the resistance of the rheostat varies, the current to the resistor varies also, which would seem to affect the current reading after passing through the resistor, then the question is that would this change in current by the rheostat affect the experiment result?

[swansont]

I would like to ask two questions...

the first one is about rheostat' date=' which its resistance could be changed. R=V/I, when R increases, three cases are possible, V increases while I keeps constant; I decreases while V keeps constant; and V increases while I decreases at the same time, which of them is the case?

 

http://hk.pg.photos.yahoo.com/ph/loiyalunait/detail?.dir=798fscd&.dnm=3d31scd.jpg&.src=ph

 

the experimental set up shown in the above diagram is used to find out the relationship between resistance, voltage and current. when a current pass through the rheostat current and voltage decreases as the rheostat consumes enery, the current then flow through the other resistor and the current after the passage is recorded, however, as the resistance of the rheostat varies, the current to the resistor varies also, which would seem to affect the current reading after passing through the resistor, then the question is that would this change in current by the rheostat affect the experiment result?[/quote']

 

 

In the first part, what is your source? That will tell you what happens to V or I, e.g. if you have a constant current source, then current will stay constant. Typically, though, you have a constant voltage.

 

In the second part, you have a constant voltage from your battery. Current will be dictated by the total resistance, but that current will pass through all components that are in series.