Did you know Timstar supply Lascells products? Looking for British designed and manufactured physics equipment?

One of the great joys of the world is understanding how something works and this is the cornerstone of Lascells thinking. They design physics apparatus with ease of use, durability and associated learning outcomes in mind. They aim to reduce setup time and unnecessary complications so that teachers can spend valuable lesson time preparing students for a future in physics and engineering.

EXPERIMENT IDEAS FOR THE LASCELLS E-FIELD DETECTOR

A way of detecting not only electrostatic charge, but also whether the charge is the same or different (negative will light blue, positive will light red), and an improvement on the delicate gold leaf electroscope that has been in use for many years.

It is more robust than the gold leaf electroscope and simple to use, and there are different accessories available to help to demonstrate charge.

Here are a few ways you can use the E-Field Detector:

Observing positive and negative charging of rods

You will need:

• E-Field Detector (EL220000)

• Acetate or glass rod

• Ebonite or polythene rod

• Silk/cotton cloth (duster)

Set up the E-Field Detector as directed (remember to connect the grounding wire and reset to zero).

Rub the acetate or glass rod with the cloth and bring the rod close to the detector – the red lights will light up indicating a positive charge.

Repeat with the ebonite or polythene rod and the blue lights will light up indicating that there is a negative charge on the rod.

How charge decreases with increasing distance

You will need:

• E-Field Detector (EL220000)

• Rod

• Silk/cotton cloth (duster)

Set up the E-Field Detector as directed (remember to connect the grounding wire and reset to zero).

Charge up the rod with the duster, and bring the rod close to the detector so the maximum number of lights light up. Slowly pull the rod away from the detector and you will see the number of lights lit decrease, showing that the electric field is decreasing with increasing distance.

√ You can attach a voltmeter to the E-Field Detector to give quantitative measurements, using the sockets on the detector (make sure you connect it the right way round, check the instructions).

The charge proof plane

You will need:

• E-Field Detector (EL220000)

• Charge proof plane (EL220010)

• Various cloths

The charge proof plane is a useful accessory to check the charge left (or gained) by the type of cloth you are using to charge the rods with.

Set up the E-Field Detector as directed (remember to connect the grounding wire and reset to zero).

Rub your cloth of choice onto the charge-proof plane and hold it near to the detector, it will light in the colour of the charge that was on the cloth (red for +ve, blue for -ve).

Observing charge by induction

You will need:

• Field Detector (EL220000)

• Ebonite rod and duster

• Charge separation rods (accessory – EL220030)

Set up the E-Field Detector as directed (remember to connect the grounding wire and reset to zero).

Place the charge separation rods, touching end-to-end, in front of the detector.

Bring a charged ebonite rod close to the end of the charge separation rod (furthest from the detector).

Holding the plastic stands only (not touching the metal rods) separate the charge separation rods.

Test each against the E-Field Detector to see that they now have opposite charges.

√ The negatively charged ebonite rod will repel electrons from the first metal separation rod towards the second one (the one nearest the E-Field Detector) – polarising the metal separation rods. When you pull the two rods apart, the one nearest the ebonite rod will be positive, the one furthest away from the ebonite rod will be negative.

For more than a century, the OHAUS name has been synonymous with precision and reliability. Here at Timstar we are happy to partner with OHAUS to bring you a full range of balances which are perfectly suited to your lab environment.

Balance Terminology

Analytical:

High precision pieces of equipment capable of weighing over a wide range and with accuracies of 1 decimal place to 2 and 3 decimal places, depending on the model and its usage. They are generally reserved for the prep room.

Precision:

Available in a wide range of capacities. Not as precise as analytical balances, but more precise than the average bench or compact scale. They also have a higher capacity than analytical balances, but a lower readability.

Top loading

Often equated with precision balances and named as such, the top pan balance is the most robust but least accurate of the three, the range is higher, but the readability is lower.

Common Balance Features

√ Locking switch: Locked to secure the delicate internal mechanism during transport.

√ Overload protection: ensures the balance’s durability.

√ Mini spirit level: ensures the balance is level before weighing for accurate results.

√ Calibration function: on most modern balances. Press to calibrate before use.

√ Tare ‘reset to zero’ button: allows you to clear the balance weight prior to weighing (meaning you can ignore the effect of the weighing vessel).

√ Under balance weighing hook: Used for weighing oversized items that do not fit well on the balance pan.

√ Draught shield: Protects the contents on the balance from air currents, creating a stable environment for getting the most accurate mass.

√ Units of measurement: As well as the usual grams measurement most balances offer different units of measurement.

A couple of the less well known are;

√ Parts counting: Parts counting allows you to count very small items into a container and the balance will tell you when you have reached the correct amount.

√ Dynamic weighing: Dynamic weighing is useful for measuring objects in motion, for example: small animals, liquids, free flowing ingredients, volatile chemicals, weighing in an unstable environment.

Search ‘OHAUS’

Navigator

Ruggedly constructed and multifunctional, the Navigator is a powerful balance that can handle a diverse range of weighing applications with features such as fast stabilisation time, overload protection at four times its rated capacity, and easy operation.

Pioneer

Offering accuracy and repeatability in essential weighing applications

Pioneer balances deliver competitive performance at an economical price. Featuring RS232 connectivity for easy communication, a backlit display, and a simple interface for uncomplicated operation.

Scout

Designed for education applications, the OHAUS Scout with large backlit LCD backed by education software is the ideal balance for your classroom. Built to endure demanding classroom applications with superior overload protection, faster stabilisation time, increased capacity, multiple connectivity options and stackable design.