Question

1. why didnt sundials work on cloudy days or at night? a) they needed electricity b) the gnomon broke c) they required sunlight to make a shadow d) people forgot how to read them

Explanation:

Sundials work by using the position of the sun to cast a shadow (the gnomon's shadow) to tell time. On cloudy days or at night, there is no direct sunlight to create the necessary shadow for the sundial to function. Option a is incorrect as electricity isn't related to sundials. Option b is incorrect as a broken gnomon isn't the reason for non - functionality on cloudy nights. Option d is incorrect as the issue isn't about people forgetting to read them but the lack of sunlight. Option c correctly states that sundials need sunlight to create the shadow for time - telling, so on cloudy days or at night (when there's no or insufficient sunlight), they don't work.

Answer:

c) They required sunlight to make a shadow