Scientists could investigate this idea by making cathode ray tubes out of different materials to see if the ray was the same.
Power is defined as
P = I*V
where I is the current and V is the voltage
Ohm's law gives us the relation betwen Voltage and current in a resistive component
V = I*R , Then
P = V² / R
We solve for R,
R = (110 V)²/ 75W = 161.33 ohms