We can block light by placing obstacles in its path, but it’s much more difficult to block sound. why?

What are the north and south poles of a solenoid change with?

Which of the following is tru about semi-conductors

Acertain half-reaction has a standard reduction potential e_red^0 = -0.94 v. an engineer proposes using this half-reaction at the cathode of a galvanic cell that e must provide at least 1.00 v of electrical power. the cell will operate under standard conditions. a. is there a minimum standard reduction potential that the half-reaction used at the anode of this cell can have? b. is there a maximum standard reduction potential that the half-reaction used at the anode of this cell can have?