Experiments: Advanced (A-level and A-level+ activities)

Description	Quantity	Product No
Baseboard LK750	1	410-8900
Baseboard LK50	1	410-3000
Lead Set LKLS	1	410-8022
DC Power Supply CU600T	1	411-1000
AC Power Supply CU600AC	1	411-1001
Component carriers:
Connecting link	10	410-5250
Lamp holder	4	410-5291
Lamps	4	410-2347
Resistor 1K	2	410-5202
Resistor 100K	1	410-5218
Resistor 10K	1	410-5203
Variable resistor 10K	1	410-5214
Thermistor	1	410-5402
LDR	1	410-5144
LED red	1	410-6420
NOT gate	1	410-6862
OR gate	1	410-6861
AND gate	1	410-6860
Op-Amp	1	410-6234
Transistor	1	410-5240
Resistor 180 ohm	1	410-5207
Resistor 33 ohm	1
Other equipment:
Cells	3
Stopwatch	1
Oscilloscope	1
Voltmeter, ammeter or multimeter	1

Resistors in Series and Parallel

• Resistors can be combined to increase or decrease their overall value.
• Students experiment with series and parallel resistor combinations before writing rules for each type.
• Students are then able to predict the value of any combination - which they can then test.

Characteristics of Electrical Components

• Introduces students to the concept of graphs that characterise a component's behaviour.
• Students then go on to make relevant measurements in order to plot characteristic graphs for a bulb, a resistor, a diode (an LED) and a thermistor.
• Students discuss the significance of the gradients of each graph
• Tasks can be extended by introducing "reverse bias", comparing the "switch on" voltage of a normal diode to an LED, the negative temperature coefficient of thermistors, and the characteristics of an LDR

EMF and Internal Resistance

• Explains the emf of a cell and its internal resistance.
• Students carry out an experiment to determine the emf and internal resistance of a cell, through plotting a graph and determining its gradient and intercept.

Kirchoff's Laws

• Describes the usefulness of Kirchoff's Laws for analysing small sections of circuits.
• Students then carry out experiments to demonstrate how the two laws work.

Potential Dividers

• Reminds students that components in series share the voltage that is across them.
• Students explore the rules for sharing voltage in potential dividers with simple resistor combinations.
• These rules are then tested and used to explain more complex and variable combinations.

Capacitors and Timing

• Demonstrates how the time a capacitor takes to charge depends on its size, and on its series resistance.

Logic Systems

• Discusses the three main types of logic gate (AND, OR and NOT) and that they are key components of microelectronic circuits.
• Students then build three circuits to show each of these types of gate in use.

Rectification

• Discusses the differences between AC and DC, and shows that some devices need either one or the other.
• Illustrates how rectification is a way to change AC into DC.
• Students work through a series of stages that explains the rectification process.
• A possible extension activity involves using a capacitor to smooth the rectified output.

Latching

• Discusses the usefulness of latching to keep an output switched on, even when the input that caused it has switched off.
• Students build a circuit that latches on, and learn to explain how it works.

Transistor Amplification

• Explains how transistors can be described as current amplifiers (although the emitter current is just proportional to the base current).
• Students carry out measurements in a circuit which will allow them to calculate the transistor's gain.

Operational Amplifiers

• Discusses that an op-amp is a versatile component that can alter input voltages in a variety of ways, depending on the circuit.
• Students build three different op-amp circuits and make measurements to compare their behaviour to gain equations for each type.

Capacitor Combinations

• Students carry out charging experiments with a variety of series and parallel capacitor combinations, and determine whether the combinations increase or decrease the overall capacitance.
• Students then learn the rules for capacitance combinations.