What is the measurement unit of luminous flux?
A:lux
B: Newton
C :joule
D: lumen

What are the phases shown in a and d called?

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.

Two point charges are separated by a certain distance. how does the strength of the electric field produced by the first charge, at the position of the second charge, change if the second charge is doubled? a. the field does not change b. the field strength decreases by half. c. the field strength doubles d. the field strength quadruples