Which of the following materials is an insulator against electric current

a- a sliver spoon
b- aluminum foil
c-a glass pane
d- a copper penny

Which accurately compares concave and convex lenses?

Assume you measured the mass of the cart to be (500 ± 1) g and the mass of the additional mass you put on the cart to be (500 ± 1) g as well. since the scale you are using in the lab cannot measure objects heavier than 600g you will have to sum up individual pieces and propagate the error. so what would be the mass and the standard error of the cart and the mass

Abar magnet cut in half will form a total ofpoles.a)fourb)eightc)two