Two particles, each a mass m, are a distance d apart. to bring a third particle, also with mass m, from far away to the point midway between the two particle an external agent does work given by:

yes

Explanation:

because no matter what voltage you connect it up to, the current always increases proportionally to the voltage.

this is because it follows ohm's law V = I X R.

(voltage = current X resistance)

so to calculate the resistance, change the formula to R = V / I giving you 60 ohm (resistor value)

the value of the resistor is always 60 ohm's, no matter which combination of voltage and current you used and measured, so it follows ohm's law, therefore being an ohmic resistor