EMF's in series how does this work ?

In summary: So the total resistance of each cell is 1 ohm and 100 ohms, respectively. Then you can use Kirchoff's voltage law to solve for the current in each cell and the voltmeter reading.In summary, a secondary cell with an e.m.f. of 2V and an internal resistance of 1ohm is connected in series with a primary cell with an e.m.f. of 1.5V and an internal resistance of 100ohm. The negative terminals of each cell are connected to the positive terminal of the other cell. A voltmeter with a resistance of 50ohm is connected to measure the terminal voltage. Using Kirchoff's voltage law, the voltmeter
  • #1
hilly
3
0

Homework Statement



A secondary cell having an e.m.f. of 2V and an internal resistance of 1ohm is connected in series with a primary cell having an e.m.f. of 1.5V and an internal resistance of 100ohm the negative terminals of each cell is connected to the positive terminal of the other cell. A voltmeter having a resistance of 50ohm is connected to measure the terminal voltage of the cells. Calculate the voltmeter reading and the current in each cell.

Ans given by book:72.8mA, 34.3mA, 1.93V

Homework Equations


Kirchoff voltage law.


The Attempt at a Solution



I can not understand how 2 cells in series can have a different current ? What concept am I missing ?
 
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  • #2
The current will change according to which cell voltage you are measuring.

The voltmeter has a resistance of 50R... (that's some "voltmeter"...)
 
  • #3
Is there a picture for the question? I'm not sure how the voltmeter is connected to measure the terminal voltage.
 
  • #4
Defennder said:
Is there a picture for the question? I'm not sure how the voltmeter is connected to measure the terminal voltage.
Sorry no picture because the textbook has no picture only the words
 
  • #5
zeitghost said:
The current will change according to which cell voltage you are measuring.

The voltmeter has a resistance of 50R... (that's some "voltmeter"...)
The book answer gives one voltage and 2 currents.
 
  • #6
Instead of thinking about 2 batteries in series, try picturing the situation as 3 objects all in parallel (the 2 cells and the 50-ohm resistor).

Don't forget to include the internal resistances as part of the cells.
 

FAQ: EMF's in series how does this work ?

What is the concept of EMF's in series?

EMF's (electromotive forces) in series refers to the arrangement of multiple sources of electrical potential difference in a circuit, where the positive terminal of one source is connected to the negative terminal of another source. This results in an overall increase in the total EMF of the circuit.

How do EMF's add up in series?

In series, the EMF's add up to create a larger total EMF. This is because the potential difference is cumulative, meaning that the potential difference of each source adds on to the previous one. For example, if two sources have EMF's of 5 volts and 3 volts, the total EMF in the circuit would be 8 volts.

What is the effect of adding more EMF's in series?

Adding more EMF's in series results in an increase in the total EMF of the circuit. This can be useful for powering larger or more complex circuits that require a higher voltage to function properly.

Can EMF's in series cancel each other out?

No, EMF's in series cannot cancel each other out. This is because the potential difference is cumulative, so even if one source has a negative EMF, it will simply subtract from the overall total, rather than canceling it out.

What are some real-life examples of EMF's in series?

One common example of EMF's in series is a battery pack, where multiple batteries are connected in series to increase the overall voltage. Another example is the wiring in a house, where multiple outlets and light switches are connected in series to create a larger circuit for electricity to flow through.

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