Hydrogen atoms are excited by a laser to the =4 state and then allowed to emit. what is the maximum number of distinct emission spectral lines (lines of different wavelengths) that can be observed from this system?

so total 6 spectral lines are possible here

Explanation:

Since the electron is at excited state of n= 4

so here we have electron from nth excited to lower possible state

here the lower most energy state is ground state

so we will have

here we know

n = 4

so total 6 spectral lines are possible here

heat the gas and measure the pressure

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it