Pokhran is a city and a municipality located in Jaisalmer district in the Indian State of Rajasthan. It is a remote location in the Thar desert region and served as the test site for India’s first underground nuclear weapon detonation.

It shot into the international limelight on 7th September 1974, when the then Indian Prime Minister Indira Gandhi verbally authorised scientists at the Bhabha Atomic Research Centre (BARC) at Trombay to detonate small and miniaturised nuclear device. Throughout its development, the device was formally called the Peaceful Nuclear Explosive (PNE) by Indian Government, but it was usually referred to as the Operation ‘Smiling Buddha’. On 11th May of 1998, 24th year after the first operation, the Atomic Energy Commission of India and the Defence Research and Development Organisation (DRDO) carried out the joint operation, known as Pokhran-ll. The AEC India detonated its four devices as part of the underground nuclear testing on Pokhran Test Range.

At high temperatures, the tungsten filament gets hot and atoms in the filament vibrate more. The electrons in the current now collide more with the atoms & more energy is needed to push the current through the filament. Hence, the resistance of tungsten increases with temperature.