1. Name the metal used to manufacture the coiled spring below - NSC Agricultural Technology - Question 2 - 2021 - Paper 1

1. Vesconite gives long life with low maintenance and low friction.
2. It is waterproof and does not swell or seize when exposed to wet conditions.
3. Vesconite is corrosion resistant, which makes it suitable in marine environments.

1. All-weather clothing, which benefits from Teflon's water-repellent properties.
2. Eyeglass lenses, where Teflon is used for anti-fogging properties.
3. Lubricants in manufacturing, providing low friction in moving parts.

The critical melting point of Teflon is approximately 327°C. Teflon begins to break down at this temperature.

1. Copper is an excellent conductor of electricity.
2. It does not rust or corrode easily, ensuring durability.
3. It is malleable, allowing for easy shaping and installation.
4. Copper wires can be easily soldered for secure connections.

1. Brass resists metal fatigue better than steel.
2. It has low-friction properties, reducing wear in moving applications.
3. Brass exhibits corrosion resistance in marine environments.
4. Brass products are generally shinier and aesthetically appealing.

1. In explosive atmospheres, where a steel hammer might create sparks.
2. In the presence of flammable vapours or when working with sensitive materials.

The resin used in glass fibre products is typically a thermosetting resin like epoxy or polyester, which provides strength, flexibility, and moisture resistance to the final product.

1. Glass fibre is lightweight, making it easier for transportation and handling.
2. It is easily repaired if damaged, ensuring long-lasting use.
3. Glass fibre has excellent resistance to water, enhancing the durability and lifespan of small boats.

The earth return system of an electric fence works by providing a low-resistance path back to the energizer through the ground. When an animal touches the live wire, it completes the circuit by using the earth as a return path, delivering a shock.

1. Poor connections in the circuit can lead to increased resistance and hence a voltage drop.
2. The presence of vegetation or debris touching the fence wire can cause undesirable grounding, leading to voltage loss.

To test the earth system of an electric fence, follow these steps:

1. Disconnect the energizer and check all ground connections for tightness and corrosion.
2. Use a multimeter to measure the voltage at the ground rod. A reading above a certain threshold indicates a poor earth connection.
3. Inspect the grounding rods to ensure they are properly driven into the soil and not exposed to moisture or corrosion.
4. Reconnect the energizer and test the system under live conditions, looking for any abnormal voltage readings.