Lascells Planck's Constant Apparatus

This quality and reliable apparatus incorporates an array of clear envelope LEDs with peak emission wavelengths in the range 464 to 940 nm. The controls allow each LED to be selected in turn and the applied voltage varied so that its electrical characteristics may be investigated. With some simple calculations, an estimate of Plancks constant may be made (the accepted value being h = 6.626 x 10 Js). By monitoring the voltage at which each LED just begins to emit light, a graph of energy input as a function of light emitted frequency can be plotted and an approximate value of Plancks constant deduced. The system is an excellent illustration of modern electronics and gives a good investigation into a difficult topic in post-16 physics. The LEDs are mounted in a self-contained box with voltage control and monitoring points for current and voltage; a voltmeter and ammeter can be connected via the integral 4 mm sockets. A protection resistor is included to prevent damage to the LEDs. Supplied complete with viewing tube. Please note: Requires a 5 V DC lab. power supply (not included). Dimensions: 260 x 145 x 100 mm (l x w x h) Weight: 0.49 kg Connectivity: 4 mm sockets Power: 5 V DC (power supply not included)