Q8. Answer Acceptable answers Mark Correctly plotted point (1) +/- ½ a small square (1) Do not accept clearly dot-to-dot (1) Smooth line through most (at least or excessive tramlining 5) crosses / points (1) Ignore any part of line after 45 (a) transposition and substitution in (iii) either order substitution mark can be scored when incorrectly transposed word/symbol Substitution: (1) 12 = 0.047 × R equation is given Transposition: (1) R = 12/0.047 255.3, 255 Evaluation: (1) R = 260 give full marks for correct answer no working power of 10 errors with no working score max 1 mark (3) (a) An explanation linking (for this first MP) (iv) ignore faster/slower current increases with  (charge/current) ignore temperature (1) with references to heat, (so) resistance decreases(1)  current flows more can or score both marks by quoting two the voltage is constant (1) with  suitable pairs of values from (so) resistance decreases  graph For full marks, there (with temperature increase)(1) must be a reference to change of either I or R with temperature (2) An explanation linking atoms / nuclei allow for 1 ) mark,electrical energy electrons / negative charges  transferred to thermal/heat (1) energy if no other scored collide with  ions/lattice/electrons (1) (2) (b) A suggestion including energy thermistor/resistor gets hot/is (ii) transfer in the thermistor/ any heated component part of the electrical circuit causes a rise in temperature of thermistor (above surroundings)(1) (1) Q9. Answer Acceptable answers Mark (a)(i) B (1)
Q8. Answer Acceptable answers Mark Correctly plotted point (1) +/- ½ a small square (1) Smooth line through most (at least 5) crosses / points (1) Do not accept clearly dot-to-dot or excessive tramlining Ignore any part of line after 45 (1) (a) (iii) Substitution: (1) 12 = 0.047 × R Transposition: (1) R = 12/0.047 Evaluation: (1) R = 260 transposition and substitution in either order substitution mark can be scored when incorrectly transposed word/symbol equation is given 255.3, 255 give full marks for correct answer no working power of 10 errors with no working score max 1 mark (3) (a) (iv) An explanation linking  current increases with temperature (1) with  (so) resistance decreases(1) or  the voltage is constant (1) with  (so) resistance decreases (with temperature increase)(1) (for this first MP) ignore faster/slower (charge/current) ignore references to heat, current flows more can score both marks by quoting two suitable pairs of values from graph For full marks, there must be a reference to change of either I or R with temperature (2) An explanation linking  electrons / negative charges (1)  collide with ions/lattice/electrons (1) atoms / nuclei allow for 1 mark,electrical energy transferred to thermal/heat energy if no other scored (2) (b) (ii) A suggestion including energy transfer in the thermistor/ any component part of the electrical circuit causes a rise in temperature of thermistor (above surroundings)(1) thermistor/resistor gets hot/is heated (1) Q9. Answer Acceptable answers Mark (a)(i) B (1) )
p2_revision_pack_mark_scheme.docx