A student uses a DC power supply to drive a current through a 20 $\Omega$ resistor, and measures the power dissipated as 80 W. The student then replaces the DC power supply with an AC power supply connected to the same resistor. To achieve the same power dissipation of 80 W, what RMS voltage should the AC power supply provide?
10 V
40 V
56.6 V
1600 V
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Create Free Account Log inThis is a free VCE Units 3 & 4 Physics practice question worth 1 mark, testing your understanding of RMS vs. DC. It falls under How are fields used in electricity generation? in Unit 3: How do fields explain motion and electricity?. Submit your answer above to receive instant AI-powered marking and personalised feedback.
In this unit students use Newton’s laws to investigate motion in one and two dimensions. They explore the concept of the field as a model used by physicists to explain observations of motion of objects not in apparent contact. Students compare and contrast three fundamental fields – gravitational, magnetic and electric – and how they relate to one another. They consider the importance of the field to the motion of particles within the field. Students examine the production of electricity and its delivery to homes. They explore fields in relation to the transmission of electricity over large distances and in the design and operation of particle accelerators. A student-designed practical investigation involving the generation of primary data and including one continuous, independent variable related to fields, motion or light is undertaken either in Unit 3 or Unit 4, or across both Units 3 and 4, and is assessed in Unit 4, Outcome 2. The design, analysis and findings of the investigation are presented in a scientific poster format.
In this area of study, students use empirical evidence and models of electric, magnetic and electromagnetic effects to explain how electricity is produced and delivered to homes. They explore the transformer as critical to the performance of electrical distribution systems in minimising power loss.
Compare alternating voltage expressed as the root-mean-square (rms) to a constant DC voltage developing the same power in a resistive component.
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