When we look at these objects in the night sky, which are we seeing as they were farthest back in time? The Pleiades (~440 light years distant)

Castor (~50 light years distant)

The Orion Nebula (~1340 light years distant)

Sirius (~9 light years distant)

Four point charges each having charge q are located at the corners of a square having sides of length a. find symbolic expressions for the following. (a) the total electric potential at the center of the square due to the four charges (use any variable or symbol stated above along with the following as necessary: ke.) vtotal= (b) the work required to bring a fifth charge p from infinity to the center of the square (use any variable or symbol stated above along with the following as necessary: w=