Sigma Instruments Co.

Gobind Nagar, Ambala, Haryana

Millikans oil Drop Apparatus is used to measure the Elementary Electric Charge. To achieve this, tiny charged droplets of oil are finely sprayed into two metal electrodes placed horizontally. Heavier drops tend to fall downwards fastly due to their thermal velocity but the lighter ones remain almost steady inside the metal electrode condenser chamber. An adjustable electric voltage is applied between the metal electrode plates which creates an electric field inside the condenser chamber. By adjusting the electric voltage, drops can be moved upwards or downwards according to their charge.

In the original design of Millikans oil drop apparatus, it was not easy to locate the oil drops in the condenser because the setting was critical. Therefore, keeping this thing into consideration, we made some improvements in the original design of this instrument, hence, making it user and student friendly.With just minor settings, Sigma Millikans Oild Drop Apparatus is capable of producing bright and large number of oil drops can be seen in the condenser enabling the students to perform the experiment withgreat accuracy and comfort.

Technical Specifications

1. Stable triangular base that supports the main steel pillar on which lamp house, condenser, microscope and atomizer system is mounted.
2. Lamp house encloses a 12Volt SMD LED and a condenser lens to focus the bright light on the oil drops. It can be adjusted in the horizontal plain by a slow motion screw.
3. Condenser plates are made of brass mounted at the top of the central pillar insulated from the rest of the apparatus. Top plate has a small hole through which sprayed oil drops enter into the condenser chamber, separated by a distance of approx 6 to 7mm. and are also provided with terminals for power supply connections.
4. Oil used by the automiser is Mustard Oil.
5. Power supply has AC 300Volt HT and AC 10Volts LT.

When Light is reflected between a spherical surface and an adjacent touching flat surface, an interference pattern is formed. This phenomenon is called Newtons Rings. The apparatus required to view this interference is called Newtons Rings Apparatus.

In Newtons Rings Apparatus, the light from the Condenser lens incidents on the plane glass inclined at 45 degrees and gets reflected vertically downwards and falls on thecombination of palno convex lens and plain glass. Some portion of the light is reflected from the lower convex side of the lens and some portionof light is reflected from the upper side of the plain glass plate. A phase difference is created between the two wave fronts that gives riseto dark and bright concentric rings which are viewed through the microscope provided with a high quality Achromatic objective, a Ramsdons eyepieceand a cross line graticule. The diameter of the rings can be measured using the micrometer.

Sigma Newtons Rings Apparatus is compact in design; consists of a heavy cast iron base with 2 levelling screws. This base carries a 4x4 steel box in which the sodium lamp is suspended from a rectangular aluminium top.

Technical Specifications

1. Least count of the micrometer provided is 0.01mm.
2. Micrometer slide total travel distance is 0-20mm.