sundial consists of a flat plate and a gnomon which casts a shadow onto the dial

As the sun  move across the sky from east to west  the shadow aligns with different hour lines which are marked on the dial in order to show the time 

The gnomon casts a broad shadow on the dial we can see the time according to the shodow
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The Brainliest Answer!
Shadows are formed in the day time due to sun's light.this shadow can be used to say the time....this is easy

1.first ,there will be a gnomon(thin rod) the sun moves in the sky,different shadows will be formed

3.when shadow of the rod casts ,  it will fall on the sundial's nos. making us to know the time......this can also be seen in the pic......

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