Transistor Switch Maximum Permissible Resistance
As a Rule of thumb all Transistors are rated at Ic/Ib=10 even if the Vce(sat) is reasonably low at a ratio of 20 or special devices with a ratio of 50, but NEVER use hFE for a switch. Rule of thumb is use 10% of hFE or 10 which ever is higher unless pushing the Ic max limits.

Thus using stead state Tungsten Lamp resistance which drops to &lt;15% R_cold when hot ( ignore that for now)


Neglect Vce(sat)= 0.7V which you used ok (close as in ballpark close...)
R_lamp=(24)/500mA = 48 Ω 
Neglect Vbe drop for now = 0.7 (ballpark)
choose R = 10 * R_load = 480 Ω


Checking 


Ib= (24-0.7)/480 Ω = 55 mA
so Ic/Ib= 500mA/55= 9.1
So add 10% ~ 20% and use 520 Ω ~ 570 Ω for cool operating transistor
500mA *0.7V = 350mW @ 0.250'C/mW for a TO-92 will be 88'C rise above 25'C room which is too hot, so choose a transistor with Vce(sat) =0.3V @ 500mA =150mW


- RULE OF THUMB using a Common Emitter SWITCH 
   - (linear load biased from same supply as load.


  Make Rb/Rc=10