Electricity Lab

Power sources

Batteries and supplies

• Dry CellA single 1.5 V cell, like an AA torch cell. The long end is +.
• BatteryDC cell pack with a fixed EMF and small internal resistance.
• DC Power SupplyVariable bench supply. Adjust the output voltage continuously.

Passive components

Resistors and loads

• ResistorFixed resistor. Obeys Ohm's law: V = I × R.
• RheostatVariable resistor: slide the contact to change the resistance in the circuit.
• Resistance BoxWooden box of standard resistors; pull plugs out to add resistance.
• Resistance WireA wire on a board. Its resistance depends on material, length and thickness: R = ρL/A.
• FuseSafety device: its thin wire melts and breaks the circuit if the current is too large.
• LDRLight-dependent resistor: more light, less resistance.
• Diodep–n junction diode: lets current through one way only. The band marks the cathode.

Output devices

LEDs, bulbs and indicators

• BulbFilament lamp. Brightness depends on the power it dissipates.
• LEDLight-emitting diode. Conducts one way once its forward voltage is reached.
• BuzzerMakes a sound when enough current flows through it.
• DC MotorTurns electrical energy into motion. Reverse the cell and it spins the other way.

Control

Switches

• SwitchOpens or closes the circuit. Click it in the workspace to toggle.
• Plug KeyLab switch: insert the brass plug to close the circuit. Click it to insert or remove.

Measurement

Meters and probes

• AmmeterMeasures current. Connect in SERIES with the component.
• VoltmeterMeasures potential difference. Connect in PARALLEL across the component.
• GalvanometerDetects tiny currents. The needle rests at the centre and swings either way.

Test materials

Conductors and insulators to test

• Test MaterialAn object held between two crocodile clips. Find out if it is a conductor or an insulator.

Wiring

Junctions and reference points

• Wire JunctionA node where several wires meet. Use it to branch for parallel circuits.
• GroundReference point (0 V) for measuring potentials.