Edexcel IGCSE Physics 2 Electricity Question Bank

power = current x voltage

Accept:
- standard symbols, e.g. P = I x V

Ignore:
- C or c for current

- substitution
- evaluation
- unit

Example:
- P = 9.6 x 230
- P = 2200
- unit = watts / W

The coil has resistance. When current flows, electrons transfer energy to the lattice ions by collisions, increasing the thermal store/temperature of the coil.

electron(s);

allow ion(s), cation(s), anion(s)

Marking points:
- substitution into formula
- conversion from $\mathrm{mA}$ to $\mathrm{A}$
- evaluation to 2 or more significant figures

Example:
$$P=230\times22\times10^{-3}$$$$P=230\times0.022$$$$P=5.1\ \mathrm{W}$$

Accept:
- $5.06\ \mathrm{W}$
- 0.022 or $\div1000$ seen anywhere in working

Ignore:
- units

Marking guidance:
- Condone a calculation of current or voltage given to at least 3 significant figures using a power of $5\ \mathrm{W}$ for full marks.

Marking points:
- substitution into $P=\frac{E}{t}$
- rearrangement
- evaluation

Example:
$$5=\frac{E}{30}$$$$E=5\times30$$$$E=150\ \mathrm{J}$$

Accept:
- ECF from 7(b)(ii)
- $$E=230\times22\times10^{-3}\times30$$
- 151.8, 152, or $153\ \mathrm{J}$
- use of E=VIt or other valid methods

Marking guidance:
- Deduct 1 mark for power-of-ten error.

energy (transferred) per unit charge (passed);

allow V=E / Q only if all terms
defined
allow work done for energy
transferred
allow coulomb for unit charge

- any attempt to add any currents together
- current = 39 mA

Marking guidance:
- 60, 65, or 82 mA scores 1 mark.

ball moves towards rod;

must be opposite(ly) charged;

allow rod and ball attract

‘opposite charges attract’ scores 2 marks

Any value greater than 5.0 cm and less than 7.2 cm.

Example:
- 6.5 cm

Any three from:
- wood has no charge
- ebonite and/or polythene are negatively charged
- glass and/or nylon are positively charged
- ebonite has the most charge
- of those that have charge, nylon is the least charged
- glass has the biggest positive charge
- ebonite has the biggest negative charge

Accept:
- nylon has the least positive charge
- polythene has the least negative charge