Markscheme for physics homework

1.       (a)

They do not depend on the weather.
There are no fuel storage problems.
They do not cause atmospheric pollution.
They can be sited anywhere.
There are no problems with transporting waste.
One wind farm can generate enough electricity to supply all of England.

          [If more than 3 ticked – deduct 1 mark for each incorrect answer]                  3

  (b)   A description to include:
1.  magnet / magnet field / N-S poles;
2.  movement (inside generator context important);
3.  coil / wire;
4.  induce V / I;                                                                                                 6

[8]

 

  2.     A

[1]

 

  3.     Direct current is only in 1 direction (1)

           Alternating current periodically changes direction (1)

Transformers only change alternating voltages /current

 or

transformers will not work on direct current   (1)

[3]

 

  4.     C

[1]

 

  5.     (i)      An explanation to include:

          1   energy / power / work;
2   input – out put / transfer;
3.  input –output different / ratio /                                                  2
correct comparison;

  (ii)   friction / heat energy produced / wires get hot / sound / noise;                         1

[4]

 

6.       Any two from:
large area needed
people unaffected by noise
wind more reliable at sea than on land;;                                                                     2
plus 1 communication mark for ensuring that spelling, punctuation                          1
and grammar are accurate, so that the meaning is clear;

[3]

 

  7.     (a)     lower (fuel) costs / cheaper (fuel); (do not allow environmental effects)         1

  (b)   One from A and one from B
A
typical start up time is long
correct comment re specified power source and start up time;
B
general comment on output to match demand
correct comment re specified power source and power output ;                       2

[3]

 

  8.     (i)      changing polarity,                                                                                             1

(ii)     Any two from:
     ·  stronger magnet;
     ·  more turns;
     ·  increase speed rotation;
     ·  placing coil on soft iron core;                                                                  2

[3]

 

  9.     (a)     (i)      number of units = 220;
220 × 2.5 = (£) 5.50 / 550p ;
[Accept (£)5.5 for both marks]
[If contradictory answers given in table and answer space, no marks]    2

(ii)     (£)68.35; [ecf from any answer given in part (i)]                                    1

  (b)   A suggestion to include one from:
1.      (night units are) cheaper / less expensive / eq;
2.      day units are more expensive;
3.      saves money / more economical;
[Reject less units used]                                                                                     1

 [4]