I-V Characteristics
Q1.
The circuit shown has four identical ammeters.
 
(a)     The table gives the current through two of the ammeters.
(i)      Complete the table to show the current through the other two ammeters.
 
Ammeter	Reading on ammeter in amps	
A1	 	
A2	0.2	
A3	0.3	
A4	 	
(2)
(ii)     Which one of the following statements is correct. Tick () the box next to your choice.
The resistance of P is more than 20 Ω.              
The resistance of P is equal to 20 Ω.                  
The resistance of P is less than 20 Ω.                
Give a reason for your choice.
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(2)
(b)     (i)      Write down the equation that links current, potential difference and resistance.
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(1)
(ii)     Calculate the reading on the voltmeter. Show clearly how you work out your answer.
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Voltmeter reading = _______________ volts.
(2)
(iii)     State the potential difference of the power supply.
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(1)
(c)     A second circuit contains an unknown component labelled X.
 
As component X is heated, the reading on the ammeter goes up. 
What is component X?
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Give a reason for your answer.
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(2)
(Total 10 marks)