A fixed resistor is connected across a variable DC power supply. The resistance of the element is kept constant throughout the experiment.
As the potential difference provided by the supply is slowly increased from an initial value ΔV0 to a final value 2ΔV0:
1. Observers notice that the temperature of the resistor rises dramatically.
2. A light‐sensitive probe aimed at the resistor senses a fourfold increase in the visible radiation it emits.
Use physical reasoning, without performing detailed numerical calculations, to analyze this situation.
(a) Describe qualitatively how the electrical power dissipated by the resistor changes when the potential difference across it is doubled while its resistance remains unchanged. Your answer should reference the relevant relationships among electric current, potential difference, resistance, and power.
(b) Explain why the observed fourfold increase in emitted light is consistent with your answer to part (a). In your explanation, connect the electrical power delivered to the resistor with the thermal and optical effects that accompany the temperature rise.
(c) The resistor is now returned to its original potential difference ΔV0, but the experimenters instead double the current through it by connecting an additional identical resistor in parallel. Qualitatively compare the power dissipated by the original resistor in this new configuration with the power it dissipated at the start of the experiment, and justify your comparison.