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# Solar cell Watch

1. can you help me draw the diagram for this question?
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2. (Original post by djmans)
can you help me draw the diagram for this question?
Read the question. All of the clues are there.

1) The manufacturer says the cell produces 1.5V e.m.f. and 100mA current.

2) Use ohms law to calculate a suitable load resistor which will draw 100mA from the cell at that voltage.

3) Draw a circuit schematic showing both the load resistor and the cell with a resistor representing it's internal resistance.

3) Place the load resistor across the cell terminals.

4) Place a voltmeter across the load and an ammeter in series with the load.

5) Measure the voltage and current and plot a graph.

6) There will be a discrepancy. At the calculated load resistance, the voltage across the load will be less than 1.5V and the current will also be less than 100mA because of that internal resistance.

So how would you go about working out what that internal resistance is?

What errors do you expect and what would you do to minimise them? CLUE: that variable resistor.
3. (Original post by uberteknik)
Read the question. All of the clues are there.

1) The manufacturer says the cell produces 1.5V e.m.f. and 100mA current.

2) Use ohms law to calculate a suitable load resistor which will draw 100mA from the cell at that voltage.

3) Draw a circuit schematic showing both the load resistor and the cell with a resistor representing it's internal resistance.

3) Place the load resistor across the cell terminals.

4) Place a voltmeter across the load and an ammeter in series with the load.

5) Measure the voltage and current and plot a graph.

6) There will be a discrepancy. At the calculated load resistance, the voltage across the load will be less than 1.5V and the current will also be less than 100mA because of that internal resistance.

So how would you go about working out what that internal resistance is?

What errors do you expect and what would you do to minimise them? CLUE: that variable resistor.
can i add the voltmeter parallel to the variable resistor below and since they say solar cell should we add a light bulb or something
4. (Original post by djmans)
can i add the voltmeter parallel to the variable resistor below and since they say solar cell should we add a light bulb or something
Yes, it makes no difference to the operation.
5. (Original post by uberteknik)
Yes, it makes no difference to the operation.
what about the bulb thing in the marking scheme it says it need a solar cell
6. (Original post by djmans)
what about the bulb thing in the marking scheme it says it need a solar cell
Your question makes no sense the way it's stated.
Any answer would be on assumption. You need to post the full question and include the mark scheme for context before I can give an answer.
7. (Original post by uberteknik)
Your question makes no sense the way it's stated.
Any answer would be on assumption. You need to post the full question and include the mark scheme for context before I can give an answer.
here
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8. (Original post by djmans)
here
The use of a light bulb is to illuminate the solar cell with a constant light intensity. This eliminates a source of error where the output voltage could otherwise fluctuate. In other words, the experiment is repeatable.

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