Christian huygens contribution in the field of physics?

Answer 1

a.) Wave Theory of Light

b.) Pendulum Clock

a.1) In 1678 the great Dutch physicist Christian Huygens (1629-1695) wrote a treatise called Traite de la Lumiere on the wave theory of light, and in this work he stated that the wavefront of a propagating wave of light at any instant conforms to the envelope of spherical wavelets emanating from every point on the wavefront at the prior instant (with the understanding that the wavelets have the same speed as the overall wave)

b.1) •He invented the pendulum clock that descends new improvements in some new inventions right now like our mechanical clocks,etc.

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