Resistor and Incandescent Lamp in Series
The cold resistance of your lamp is only around 1 Ohm. As such most of the voltage is being dropped over the resistor.







simulate this circuit &ndash; Schematic created using CircuitLab

If you want to drive the lamp from 5v you need to measure the hot current through the lamp at 1.5V so you can calculate the hot resistance. Knowing that you can select the right size of resistor. Be aware it will be small and will need to be high wattage.