Current from a charged capacitor lights a bulb. as time goes on the brightness of the

Capacitor is a device which is used to store the energy in it

This device can store the energy in the form of electrostatic field energy

This is given by formula

As we connect a charged capacitor to a light bulb the charge on the plates of capacitor will start flowing from one plate to other plate and during this charge flow the bulb will glow

As the charge from one plate move to another plate positive charge of one plate will discharge the negative charge of another plate and this will discharge the whole capacitor with time

So with time the glow of bulb or brightness of bulb that is connected across a capacitor will decrease

temp rises, and expansion

the entire statement is true and correct.  

there's no diagram, nothing is illustrated, and no question is asked.