The luminous dials of watches are usually made by mixing a zinc sulphide phosphor
Channel: Doubtnut
Date: 02/08/2020

The luminous dials of watches are usually made by mixing a zinc sulphide phosphor with an `alpha`-particles emitter. The mass of radium (mass number `226,half-life 1620 years`)that is needed to produce an average of `10` alpha`-particles per second for this purpose is