Identify the materials necessary to create an electromagnet

What would the difference of spectral lines emitted by hydrogen gas in distant galaxies which is normally found at a wavelength of 21 cm on earth, be observed at 21.1 centimeters?

Afrequency generator sends a 550 hz sound wave through both water and ice. what is the difference in wavelength between the wave produced in ice and the wave produced in water?

Due sun 06/09/2019 11: 59 pm skip navigation questions correct q 1 [1/1] correct q 2 [1/1] correct q 3 [1/1] untried q 4 (0/1) untried q 5 (0/1) untried q 6 (0/1) untried q 7 (0/1) untried q 8 (0/1) untried q 9 (0/1) untried q 10 (0/1) grade: 3/10 print version start of questions two cyclists, 42 miles apart, start riding toward each other at the same time. one cycles 2 times as fast as the other. if they meet 2 hours later, what is the speed (in mi/h) of the faster cyclist?