New (Old Stock) Electronic Vacuum Tube in original manufacturer's packaging.

To show that like magnetic poles repel each other by placing three or more ring magnets on a non-magnetic stand. Comprises five colored ring magnets (o.d. x i.d. x h), 32 x 16 x 6mm magnetised parallel to the axis, equipped with an acrylic rod mounted on a plastic base. The magnets float in the air, one over the others and spring back up when pushed down.

For generating static electric charges and causing electric discharges. Relative to Van de Graaf it produces higher current with lower voltage. Consists of two high resistance plastic disks of diameter 25cm approx, with equally spaced metal sectors. The discs are supported in two rigid upright supports, rotating in opposite directions with a hand crank. Provided with a system of induced charge collecting brushes, adjustable ball-ended electrodes and cylindrical Leyden jar capacitors for obtaining higher potential. Produces substantial opposite charges which are deposited in the capacitors and on metal spheres. A rapid sequence of sparks can be generated by lowering the systems capacitance. Mounted on insulated wooden base.

For showing the molecular nature of magnetism. Can be temporarily magnetised by stroking with a magnet and demagnetised by shaking when the filings fall out of line. Consists of a (borosilicate) glass tube 10cm long with a bulb at one end filled with iron filings.

Magnetic chips in a 50 gm vial.

For observing magnetic field. Grease free filing in plastic bottles. Pack of 500g.

For reading of topographical and tourist maps and determination of azimuthal location of a given place. Suitable for overhead projector. Transparent design. Diameter 50mm with black and red magnetised needle. Mounted on a transparent plastic base with 0-6cm x 1mm scale on bevelled end of the base plate. Full circle divided into 360ß with N,S,E and W directions indicated. Graduated every 5ß and labelled in 60ß increments. The needle housing is liquid filled to damp oscillations in just 5 seconds. The red tip indicates north. Meridian lines help in accurate plotting of angles. Adjustable wrist strap. Made in Russia.

For plotting and exploring magnetic field. In a plastic case with a four color graduated dial. Full circle divided into 360ß with N, W, S, E, etc. directions indicated. Graduated every 5ß and labelled in 15ß increments. The red tip indicates north. Diameter 38mm.

Useful for student demonstrations, plotting magnetic fields etc. Made from magnetic steel strips. Painted red and stamped with N and S to indicate north and south poles. Supplied in pairs with cardboard separator and plated soft iron keepers.

For studying magnetic phenomena such as operation of a compass, testing of magnetic poles, finding the direction of electric current etc. Consists of a magnetised steel needle about 150mm long with brass bearing pivoted on a non-magnetic metal stand. North pole is marked in red. The needle when not in use is reversed and kept in the main rod for safety.

For transferring electrostatic charges from one body to another such as Leyden jars and electroscopes. Consists of a plated brass disc of diameter 25mm on a 15cm long insulated handle.

Approximate dimensions:

Used in conjunction with plastic beads and ring magnets for motion and collision studies in physics and for other applications. Can be magnetised along any side.

For collision studies in physics and other applications such as focussing magnets etc. Charged on the faces.

Suitable for laboratory use. Approximate outside height about 28mm and outside width about 26mm painted red with keeper.

For having high magnetic field. Grounded on all sides.

Strong magnets for laboratory demonstration work, magnetizing needles, etc. Ideal for extended classroom use. Painted red and north pole marked. Supplied in pairs between plated keepers and a plastic separator.

Suitable for many experimental and demonstration needs in a general science and physics laboratory. Traditional style. Made from 5mm thick and approx. 12mm wide steel strips except for the largest size which is about 15mm wide. Painted red and stamped with N and S to indicate north and south poles. Supplied with soft iron plated keeper (armature).

For tracing the magnetic fields of bar magnets. Consists of a magnetic needle encased in cylindrical aluminum case with glass top. Card dial.

For laboratory use as a variable series resistance or as a potentiometer. Can control current and voltage. Made from heat resistant, air cooled, hollow porcelain tube closely wound with a resistance wire of copper nickel alloy which is previously oxidised to provide perfect insulation. The end supports are made of metal with provision for screw mounting. A bakelite slider carries a phosphor bronze contact which can be moved rapidly and smoothly and can rest anywhere along the winding. The insulation is sand-papered off where the slider makes contact. Resistance in ohms and current carrying capacities are engraved on contact carriage. Three terminals are provided for electrical connections, one at each end of the winding and the third at one end of the slide rod so that the unit can be used either as a rheostat or as a potentiometer. Available with a variety of resistances and current carrying capacities. Power ratings (watts) can be calculated as Watts = (Current in amperes)2 x Resistance in ohms. Caution: Rheostat of unprotected design should not be used on electric supplies more than 50 volts.

As a substitute for iron filings for studying the phenomenon of magnetic fields. Form clusters and chains between unlike poles of magnets. Polished, hardened spheres of diameter 3mm. Pack of 100.

To provide external magnetic field where required and to change the rate of magnetic flux passing through a coil. Consists of a plastic spool with windings of insulated copper. End plates have brass binding posts. Capacity 10 amperes when used intermittently and 5 amperes when used continuously.

For studying magnetic induction properties produced by electric current and the effect of an iron core, etc. Consists of a plastic spool with windings of enamelled copper wire having brass binding posts on square end supports. Includes a soft iron core rod of diameter 18cm and instructions.

Model of lifting magnet used in industry, such as scrap metal lifter. Consist of two plastic bobbins wound with enamelled copper wire and mounted on each arm of a soft iron U-core. Each of the bobbins is fitted with two 4mm socket binding posts. Includes an armature with hook to be used as a lifting ring. Operates on 3-6 Volts D.C. Overall length 100mm.

Size (l x w), 125 x 50mm with 4mm socket binding post terminal.

For electrolysis of reactive materials like hydrochloric acid and other compounds. Suitable alternative to platinum. Size (l x d), 150 X 5mm. Alligator clips can be used for making wire connections.

For experiments in detection of electric charge and determination of polarity. Consists of an Erlenmeyer flask 250mL, and a plated rod with a knob of diameter 16mm ( 2/3in) passing through a rubber stopper. A pair of aluminium leaves are suspended from the rod.

For measuring the quantity of electricity from the mass of copper deposited on one of its electrodes. Consists of three copper plates suspended from a bakelite cover of a plastic jar. Outer two electrodes acting as double anode are connected to one binding post on the top. The third inner copper plate fixed to another binding post acts as a cathode and can easily be removed for weighing.

More sensitive instrument as leaf deflection is unaffected by air currents or by charges residing on the case. Reacts only to charges which are intentionally brought near or put on them. Comprised of a box made of aluminium with two transparent glass windows to shut out air currents and a plated metal support rod entering from the top through a polyethylene insulator. Two leaves of thin aluminium foil are suspended from the support rod. Supplied with three pairs of aluminium leaves.

To produce high voltage alternating current or pulses of high voltage current from a low voltage direct current source. Suitable for use with gas-filled discharge tubes, vacuum tubes, eudiometers and for general laboratory work. Comprised of two coils fully enclosed in a polished wooden case with binding posts. Includes adjustable vibrator system, primary current polarity reversal and off-on switch, a condenser enclosed in the box and special alloy contacts. Spark gap at the discharge points can be adjusted by sliding rods back and forth. Requires 6-12 volt power source such as a battery.

Useful as a basic component for any electrical laboratory. Mounted on bakelite base. Allows visible connection for easy use. With screw holes and suitable for bench fixing and panel mounting. Available in four configurations.

Comprised of two or more brass blocks fitted with brass terminals and mounted on a black bakelite base. Tapered plugs with bakelite moulded tops fit into the tapered holes between the blocks providing low resistance contact. With rubber feet.

For providing momentary contact in electrical circuits which are normally open. Can also be used in morse code applications. Consists of a bakelite base with two 4mm socket binding post terminals. Circuit is closed with plated spring hard brass strip with insulated knob. Silver contacts.

For wheatstone bridges and potentiometers. A brass metal knife edge is mounted on one end of an insulated handle with a 4mm socket binding post terminal on the other end. Overall length 100mm. Pack of 10 pieces.

Improved version of simple meter bridge. For precise measurement of an unknown electrical resistance and for comparing nearly equal resistances without determination of the end-resistances.

For demonstrating the attraction and repulsion of electric charges. Consists of a an insulated brass pillar and hook on a base. Supplied with two colored pith balls with strings attached.

For investigating strength and direction of a magnetic field due to a current-carrying wire as a long straight conductor or as a coil of one or more turns. Comprised of a non-magnetic stand about 30cm high with pegs for fixing the surrounding coils, a punched platform and a 50cm diameter compass. Supplied with 3m long flexible copper wire and alligator clips.