The enhanced greenhouses effect is a) a natural process b) a human process c) a natural process that is added by humans d) none of the above

Which of the following energy sources is not an example of renewable energy? a. a wind turbine farm b. a clean-burning, coal-fired electric plant c. a hydroelectric dam d. a solar panel mounted on a home

Which revelation resulted from the observation of the spectrum of different galaxies? a. there were more galaxies whose spectrum was blueshifted b. there were no galaxies whose spectrum was redshifted c. there were more galaxies whose spectrum was redshifted d. there were no galaxies whose spectrum was blueshifted

Renaldo and nasreen build an electromagnet by wrapping a wire around a nail and connecting the wire to both terminals of a battery. when they test the electromagnet, it can pick up 6 paper clips. their teacher wants all groups to pick up at least 10 paper clips. what could renaldo and nasreen do to increase the number of paper clips their electromagnet picks up?