Question

Sundails cannot be used in night .Give reason?

Answer 1

In sundial, we measure time using the shadow formed by the object due to the positioning of the celestial body - sun.
During the night, there is darkness or absence of sun due to which we can use a sundial.

In simple words,
Sundial can be be used only during the daytime as shadow is casted due to sunlight, not during the night

Answer 2

sundial cannot be used in night due to darkness.we can use sundial only in day time.