GCSE Physics: February 2014

1. (a) friction;
electrostatic;
electrons;
attract; 4

(b) (i) correct direction of movement shown (towards metal plates); 1

(ii)     An explanation to include:
     · repelled from positive grid;
     · attracted to negative plates;                                                             2
[Allow like charges repel/unlike charges attract for 1 mark]

(iii) to make dust particles fall off/
in order to collect dust particles/to clean the plates; 1

[8]

2. (a) (i) V across lamp; 1

(ii) A in series; 1

(iii) thermistor/variable resistor in series; 1

(b) A calculation to include:

1. V = IR;

2. 12 = 1.6 × R;

3. R = 7.5;

4. Ohms; 4

(c) curve showing increasing R/decreasing gradient with voltage;;
starts at origin;
[Accept straight line through origin for two marks) 3

[10]

3. (a) drag/resistance/force/push/thrust/upthrust;
air/atmosphere;
[Reject wind/friction] 2

(b) 56; 1

(c) (i) pull of Earth/weight/gravitational pull/downward (pull) greater than upward (push)/there is resultant force downwards;
[Allow gravity] 1

(ii) both forces the same/balanced/equal/resultant force is zero/OWTTE; 1

(d) (i) speed decreases;
new lower terminal velocity/horizontal region shown;
(Independent marking points) 2

(ii) An explanation to include three from:

· air resistance increases;

· at start upward force greater than downward force;

· eventually forces balance;

· larger surface area;

· air resistance decreases as parachutist slows down; 3

[10]

4. (a) (idea of) time for half of undecayed nuclei/atoms to decay
OR (idea of time) for activity/count rate halved; 1

(reject mass changes)

(b) 1000÷2 [any other value (in range 500-1000)÷2]; 2

(check graph)

50 (47-53) (min);

(ignore unit)
(or alternative calculation for 2 marks)
[Reject 100/2 =50 for both marks]

(ignore units)

(ii) any two from:
contamination idea;

e.g. still waste there/soil contaminated

opinion/perception of risk/worry/fright;
radioactivity can be harmful/dangerous/cause cancer/mutations;
2 Bq (or ecf from (c)(i)/only 2 half lives/remains radioactive for long time; 2

[6]

5. A

[1]

6. B

[1]