If the slight resistance you feel from a light switch (when you flick it) is the
reaction force, what is the action force?
OA) flicking the switch
OB) the light turning on
OC) friction between your finger and the switch
OD) the switch moving from the "off" to the "on" position

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?