When the switch at the base of transistor is open no base current flows in it so transistor remains in cutoff state. No collector current flows the transistor acts as an open switch. The collector voltage is equal to collector voltage Vcc= Vcc=10V
When the switch is closed due to heavy forward biasing of the transistor the transistor goes into saturation and collector current starts flowing and led turns ON the transistor acts as closed switch and collector voltage drops to zero Vc=0
