AQA A-level Physics Potential Dividers Mark Scheme

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Mark schemes
B
1 [1]

(a) (i) 1/R total = 1/(40) +1/(10+5) = 0.09167
2 R total = 10.9 kΩ
3

(ii) I = .9 k = 1.1 mA
1

(b)
position pd / V

AC 6.0

DF 4.0

CD 2.0

C.E. for CD
3

(c) (i) AC: no change
constant pd across resistors / parallel branches(AE)
no CE from first mark
2

(ii) DF: decreases
as greater proportion of voltage across fixed / 10 k Ω resistor
no CE from first mark
2
[11]

(a) 1 joule per coulomb (or equivalent)
3
B1
allow watt per amp
1

(b) (i) Use of potential divider formula

C1
allow 1 for 4.05 (V) or current of 2.25 (mA)

4.95 (V)

A1
2

(ii) reduced current

B1
1
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(iii) use of parallel resistor formula

C1

leading to 1.72 (kΩ)

C1

pd = 4.4 (V)

A1
3

(iv) potential divider can provides sensitive control of current (from 0 - 1.1 mA)

B1
allow pot div can provide zero current and variable resistor gives
larger current

variable resistor can provide larger current but cannot get near 0 A owtte

B1
2
[9]

(a) potential divider or potentiometer
4
B1
1

(b) minimum 4 (V)

B1

variable R 8Ω

B1

max I 12 V

B1

variable R 0 (Ω)

B1
4




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