Planck's Constant By Cs Photocell

Einstein postulated that light consists of a quantum of particles, called photon whose energy E is proportioned to the frequency n, by an equation, E = hn, where h is Planck's constant.

In this experiment, narrow band interference filters are used to select wave length. Each filter selects precisely one spectral line from the light of a high pressure mercury lamp. The monochromatic light falls on the cathode of the photocell. A capacitor, connected between cathode and anode of photocell, charged by anode, is used. Electrometer amplifier is used to measure the voltage at capacitor without current.

Features:

• Multipurpose electrometer amplifier & power supply.
• Cs photo cell.
• Monochromatic light source may be used in many other experiments also.
• Heavy, rigid and stable Optical bench (made of Al extrusion)
• Saddle can hold rod from 8 to 15mm.

Objectives:

• To determine Planck’s Constant by Cs Photocell.

Technical Data:

• Optical bench : Al exclusion, L = 1.5 mtr. with Scale, Triangular shape with end stop, 4 point levelling (steel screw).
• Power supply : 2,3,4,5,6,8,10 & 12VAC full wave rectified, unsmoothed & unregulated D.C, Resettable thermal trip, Input 230 V AC,50 Hz.
• Mercury light : Starting Voltage 470 Volts, Input Voltage 220 Source volts, 50 Hz, Lamp House 250 x 100mm (L x dia.) Aperture dia 25mm, Mercury Lamp 125W.
• Electrometer : Input Impedance >1013 W,Input Current < 0.5pA, Output Voltage up to +10V, Output Current 5mA, (Short Circuit Protected), Output impedance <1W,Supply Voltage 12V AC.
• Photocell : Photocell Cs, vacuum tube, Output 4 m m safety socket, Mounting rod 10mm dia.
• Color Filter set : Red 635nm, Orange 570nm,Yellow 540nm, Green 500nm, Blue 460nm.

Scope of Delivery:.

• 1 Power Supply 12V AC/DC 5Amp
• 1 Photocell
• 1 Mercury Light Source
• 1 Convex lens in holder
• 1 Iris Diaphragm
• 1 Set of Color Filters
• 1 Set of Interference filter (optional)
• 1 Electrometer Amplifier
• 1 Optical bench triangular
• 1 Fixed slider
• 1 Accessory set (push switch, capacitor 100pF, red lead 50 & 100cm, black lead 50 & 100cm, yellow lead 50 & 100cm, earthing lead, Digital multimeter)
• 1 Transversal slider

• 1 Power Supply 12V AC/DC 5Amp
• 1 Photocell
• 1 Mercury Light Source
• 1 Convex lens in holder
• 1 Iris Diaphragm
• 1 Set of Color Filters
• 1 Set of Interference filter (optional)
• 1 Electrometer Amplifier
• 1 Optical bench triangular
• 1 Fixed slider
• 1 Accessory set (push switch, capacitor 100pF, red lead 50 & 100cm, black lead 50 & 100cm, yellow lead 50 & 100cm, earthing lead, Digital multimeter)
• 1 Transversal slider