CORE OBJECTIVES:

4.2.1 Electric charge

•  State that there are positive and negative charges
• State that positive charges repel other positive charges, negative charges repel other negative charges, but positive charges attract negative charges
•  Describe simple experiments to show the production of electrostatic charges by friction and to show the detection of electrostatic charges
• Explain that charging of solids by friction involves only a transfer of negative charge (electrons)
•  Describe an experiment to distinguish between electrical conductors and insulators
• Recall and use a simple electron model to explain the difference between electrical conductors and insulators and give typical examples

EXTENDED/SUPPLEMENT OBJECTIVES:

• State that charge is measured in coulombs 8 Describe an electric field as a region in which an electric charge experiences a force
• State that the direction of an electric field at a point is the direction of the force on a positive charge at that point
• Describe simple electric field patterns, including the direction of the field:
• (a) around a point charge
• (b) around a charged conducting sphere
• \(c) between two oppositely charged parallel conducting plates (end effects will not be examined)

4.2.2 Electric current 

CORE OBJECTIVES:

• Know that electric current is related to the flow of charge
• Describe the use of ammeters (analogue and digital) with different ranges
• Describe electrical conduction in metals in terms of the movement of free electrons
•  Know the difference between direct current (d.c.) and alternating current (a.c.) 

EXTENDED/SUPPLEMENT OBJECTIVES:

• Define electric current as the charge passing a point per unit time; recall and use the equation I = Q t
•  State that conventional current is from positive to negative and that the flow of free electrons is from negative to positive

4.2.3 Electromotive force and potential difference

CORE:

• Define electromotive force (e.m.f.) as the electrical work done by a source in moving a unit charge around a complete circuit
•  Know that e.m.f. is measured in volts (V)
•  Define potential difference (p.d.) as the work done by a unit charge passing through a component
•  Know that the p.d. between two points is measured in volts (V)
• Describe the use of voltmeters (analogue and digital) with different ranges

EXTENDED/SUPPLEMENT OBJECTIVES:

•  Recall and use the equation for e.m.f. E = W/Q
• Recall and use the equation for p.d. V = W/Q

4.2.4 Resistance

CORE:

• Recall and use the equation for resistance R = V I
• Describe an experiment to determine resistance using a voltmeter and an ammeter and do the appropriate calculations
• State, qualitatively, the relationship of the resistance of a metallic wire to its length and to its cross-sectional area 

EXTENDED/SUPPLEMENT OBJECTIVES:

• Sketch and explain the current–voltage graphs for a resistor of constant resistance, a filament lamp and a diode
•  Recall and use the following relationship for a metallic electrical conductor:
• (a) resistance is directly proportional to length
• (b) resistance is inversely proportional to cross-sectional area

4.2.5 Electrical energy and electrical power

CORE:

• Understand that electric circuits transfer energy from a source of electrical energy, such as an electrical cell or mains supply, to the circuit components and then into the surroundings
•  Recall and use the equation for electrical power P = IV
• Recall and use the equation for electrical energy E = IVt
• Define the kilowatt-hour (kWh) and calculate the cost of using electrical appliances where the energy unit is the kWh

EXTENDED/SUPPLEMENT OBJECTIVES:NONE