Communication with submerged submarines via radio waves is difficult because seawater is conductive and absorbs electromagnetic waves. penetration into the ocean is greater at longer wavelengths, so the united states has radio installations that transmit at 76hz for submarine communications. what is the approximate wavelength of those extremely low-frequency waves? 500 km1000 km2000 km4000 km

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 2 options: the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the cold balloon expands and rises. the warm balloon shrinks and sinks. the warm balloon expands and rises. the cold balloon shrinks and sinks.