SOLVE THIS!!!!!!!

[tech master 117]

in a circuit two resistors each of 2 Ω is connected in parallel to a cell such that a current of 1.2 Amps flows through it now when those same two resistors are connected in series a current of 0.4 Amps is detected in the ammeter.(taking resistance of wire as zero)calculate
1)internal resistance of cell
2)EMF of cell
GOOD LUCK!!!!!!

 

[jpanhalt]

Spoiler

EMF= 1.8V, R(cell) = 0.5 Ω

John

 

[JimB]

What about the ammeter, do we ignore its resistance as well.

JimB

 

[Ian Rogers]

Not hard...

jpanhalt I think thats wrong!!

 

[jpanhalt]

I suspect there are different understandings of the English -- subject verb agreement and such. This is how I understood the description:

R3=battery internal resistance. The current is current through the battery. How about posting your answer hidden as spoiler? Since ammeter resistance wasn't mentioned, I assumed one was not in the circuit. That is, it was a Hall or similar type ammeter.

John

 

[Ian Rogers]

Spoiler

EMF 1.62v battery res 0.16 ohm

What I got!

 

[Ian Rogers]

Sorry a bit of adjustment...

Spoiler

EMF 1.68v and resistance 0.2 ohm

 

[Les Jones]

I got the same answer as John.

I would like to use the "Spoiler" option to show how I worked it out.
How is the "spoiler" option used ?

Les.

 

[Ian Rogers]

There are two senario's

 

[Ian Rogers]

Okay Ignore me..... I had written down 1.4A and 0.4A....

Sorry!!!

 

[jpanhalt]

Ian Rogers Join the club.
Les Jones Just use spoiler tags like you use code tags:

[spoiler] text [/spoiler]

John

 

[Les Jones]

Spoiler

R is the internal resistance of the cell. V is the cell EMF

1.2 = V/(R+1) so V = 1.2(R+1)

0.4 = V/R+4) so V = 0.4(R+4)


So 1.2(R+1) = 0.4(R+4)

1.2R + 1.2 = 0.4R +1.6
1.2R - 0.4R = 1.6 - 1.2
0.8R = 0.4
R = 0.4/0.8
R = 0.5


V = 1.2R +1.2 = 0.6 + 1.2
V = 1.8

Thanks John.

Les.

 

[JoeJester]

Spoiler

works with images too!!!

 

[jpanhalt]

That's good to know, did you just discover it? How does it relate to the question on the floor? This may help you: https://xenforo.com/community/help/bb-codes

John

 

[JoeJester]

I just tried it. I'm sure we could use the other bbcodes as well.

 

[JimB]

I just tried it. I'm sure we could use the other bbcodes as well.

Lets' give it a try:

• Bullet 1
• Bullet 2

1. Entry 1
2. Entry 2

Left-aligned​

Center-aligned​

Right-aligned​

A bit of a thread hijack going on here, Dick Turpin would be pleased.

JimB

 

[Les Jones]

I thought there would have been more people answering the question. It would have been interesting to see the methods used.

Les.

 

[cowboybob]

Sim'ed it.

Sadly, "bit-banged" the values until I got the answer... .

 

[Ian Rogers]

I thought there would have been more people answering the question. It would have been interesting to see the methods used.

Les.

Same as you ( even though the question was written down wrong ) For 1.4A and 0.4A it was correct!!

 

[jpanhalt]

Les Jones My solution was very similar to yours. I just wrote the equations for each case, equated them, and solved for one variable. Then substituted to get the other variable.
I would have shown my work, but I am terrible with LaTex.


John