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1 (a) (i) Describe how you would make a direct measurement of the emf ɛ of a cell, stating
the type of meter you would use.
______________________________________________________________
______________________________________________________________
(1)
(ii) Explain why this meter must have a very high resistance.
______________________________________________________________
______________________________________________________________
(1)
(b) A student is provided with the circuit shown in the diagram below.
The student wishes to determine the efficiency of this circuit.
In this circuit, useful power is dissipated in the external resistor. The total power input is the
power produced by the battery.
Efficiency =
The efficiency can be determined using two readings from a voltmeter.
(i) Show that the efficiency = where ɛ is the emf of the cell
and V is the potential difference across the external resistor.
(1)
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(ii) Add a voltmeter to the diagram and explain how you would use this new circuit to
take readings of ɛ and V.
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(c) Describe how you would obtain a set of readings to investigate the relationship between
efficiency and the resistance of the external resistor. State any precautions you would take
to ensure your readings were reliable.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
(d) State and explain how you would expect the efficiency to vary as the value of R is
increased.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
(Total 9 marks)
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Page 3 of 30
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A student has a diffraction grating that is marked 3.5 × 103 lines per m.
2
(a) Calculate the percentage uncertainty in the number of lines per metre suggested by this
marking.
percentage uncertainty = ____________________ %
(1)
(b) Determine the grating spacing.
grating spacing = ____________________ mm
(2)
(c) State the absolute uncertainty in the value of the spacing.
absolute uncertainty = ____________________ mm
(1)
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Page 4 of 30
1 (a) (i) Describe how you would make a direct measurement of the emf ɛ of a cell, stating
the type of meter you would use.
______________________________________________________________
______________________________________________________________
(1)
(ii) Explain why this meter must have a very high resistance.
______________________________________________________________
______________________________________________________________
(1)
(b) A student is provided with the circuit shown in the diagram below.
The student wishes to determine the efficiency of this circuit.
In this circuit, useful power is dissipated in the external resistor. The total power input is the
power produced by the battery.
Efficiency =
The efficiency can be determined using two readings from a voltmeter.
(i) Show that the efficiency = where ɛ is the emf of the cell
and V is the potential difference across the external resistor.
(1)
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Page 2 of 30
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(ii) Add a voltmeter to the diagram and explain how you would use this new circuit to
take readings of ɛ and V.
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(c) Describe how you would obtain a set of readings to investigate the relationship between
efficiency and the resistance of the external resistor. State any precautions you would take
to ensure your readings were reliable.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
(d) State and explain how you would expect the efficiency to vary as the value of R is
increased.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
(Total 9 marks)
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Page 3 of 30
, theonlinephysicstutor.com
A student has a diffraction grating that is marked 3.5 × 103 lines per m.
2
(a) Calculate the percentage uncertainty in the number of lines per metre suggested by this
marking.
percentage uncertainty = ____________________ %
(1)
(b) Determine the grating spacing.
grating spacing = ____________________ mm
(2)
(c) State the absolute uncertainty in the value of the spacing.
absolute uncertainty = ____________________ mm
(1)
@TOPhysicsTutor facebook.com/TheOnlinePhysicsTuto
Page 4 of 30
