- Understand the concept of electric charge and charge carriers
- Understand the process of charging by friction and use the concept to explain related day to day observations
- Understand that, for any point outside a spherical conductor, the charge on the sphere may be considered to act as a point charge at its centre
- State Coulomb’s law
- Recall and use 𝐹 =Qq/4piEor^2 for the force between two point charges in free space or air
- Compute the magnitude and direction of the net force acting at a point due to multiple charges
- Describe an electric field as a region in which an electric charge experiences a force
- Define electric field strength as force per unit positive charge acting on a stationary point charge
- Calculate forces on charges in uniform electric fields of known strength
- Use 𝐸 = Q/4piEor^2strength of a point charge in free space or air
- Illustrate graphically the changes in electric field strength with respect distance from a point charge
- Represent an electric field by means of field lines
- Describe the effect of a uniform electric field on the motion of charged particles
- Understand the concept of electric flux of a surface
- State Gauss law and apply it for a field of a charged sphere and for line charge
- Understand that uniform field exists between charged parallel plates and sketch the field lines
- Define potential at a point as the work done per unit positive charge in bringing a small test charge from infinity to the point
- Use electron volt as a unit of electric potential energy
- Recall and use 𝑉 =Q/4piEor for the potential in the field of a point charge
- Illustrate graphically the variation in potential along a straight line from the source charge and understand that the field strength of the field at a point is equal to the negative of potential gradient at that point
- Understand the concept of equipotential lines and surfaces and relate it to potential difference between two points
- Recall and use 𝐸 = ∆v/ ∆x to calculate the field strength of the uniform field between charged parallel plates in terms of potential difference and separation
- Show understanding of the uses of capacitors in simple electrical circuits b. Define capacitance as the ratio of the change in an electric charge in a system to the corresponding change in its electric potential and associate it to the ability of a system to store charge c. Use 𝐶 = Q/v d. Relate capacitance to the gradient of potential-charge graph
- Derive 𝐶 = EoA/d , using Gauss law and 𝐶 =Q/v , for parallel plate capacitor b. Explain the effect on the capacitance of parallel plate capacitor of changing the surface area and separation of the plates c. Explain the effect of a dielectric in a parallel plate capacitor in
- Derive formula for combined capacitance for capacitors in series combinations b. Solve problems related to capacitors in series combinations c. Derive formula for combined capacitance for capacitors in parallel combinations d. Solve problems related to capacitors in parallel combinations
- Energy stored in a charged capacitor a. Deduce, from the area under the potential-charge graph, the equations 𝐸 = 1/2𝑄𝑉and hence 𝐸 = 1/2𝐶𝑉^2 for the average electrical energy of charged capacitor
- Effect of dielectric b. Show understanding of a dielectric as a material that polarizes when subjected to electric field c. Explain the effect of inserting dielectric between the plates of a parallel plate capacitor on its capacitance
- Understand the concept that potential difference between two points in a conductor makes the charge carriers drift
- Define electric current as the rate of flow of positive charge, Q = It c. Derive, using Q=It and the definition of average drift velocity, the expression I=nAvq where n is the number density of free charge carriers
- Ohm’s law Ohm’s law; Electrical Resistance: resistivity and conductivity a. Define and apply electric resistance as the ratio of potential difference to current b. Define ohm , resistivity and conductivity c. Use R = ρl /A for a conductor d. Explain, using R = ρl /A, how changes in dimensions of a conducting wire works as a variable resistor e. Show an understanding of the structure of strain gauge (pressure sensor) and relate change in pressure to change in in resistance of the gauge f. Show an understanding of change of resistance with light intensity of a light-dependent resistor (the light sensor) g. Show an understanding of change of resistance of n-type thermistor to change in temperature (electronic temperature sensor)
- Current-voltage relations: ohmic and non-ohmic a. Sketch and discuss the I–V characteristics of a metallic conductor at constant temperature, a semiconductor diode and a filament lamp d) state Ohm’s law b. State Ohm’s law and identify ohmic and non-ohmic resistors
- Derive, using laws of conservation of charge and conservation of energy, a formula for the combined resistance of two or more resistors in parallel b. Solve problems using the formula for the combined resistance of two or more resistors in series c. Derive, using laws of conservation of charge and conservation of energy, a formula for the combined resistance of two or more resistors in parallel d. Solve problems using the formula for the combined resistance of two or more resistors in series and parallel to solve simple circuit problems
- Potential divider a. Understand the principle of a potential divider circuit as a source of variable p.d. and use it in simple circuits b. Explain the use of sensors (thermistors, light-dependent resistors and strain gauges) in potential divider circuit as a source of potential difference that is dependent on temperature, illumination and strain respectively
- Electromotive force of a source, internal resistance a. Define electromotive force (e.m.f.) in terms of the energy transferred by a source in driving unit charge round a complete circuit b. Distinguish between e.m.f. and potential difference (p.d.) in terms of energy considerations c. Understand the effects of the internal resistance of a source of e.m.f. on the terminal potential difference
- Work and power in electrical circuit a. Derive from the definition of V and I, the relation P=IV for power in
- electric circuit b. Use P=IV c. Derive P=I2 R for power dissipated in a resistor of resistance R and use the formula for solving the problems of heating effects of electric current
