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Massachusetts Comprehensive Assessment System

2015, High School Intro Physics

  Question 12: Open-Response  
The diagram below shows a simplified schematic for an adjustable electric heating blanket. The switch may be connected to point W, X, or Y depending on the desired level of warmth.
The diagram is of a circuit with a battery, a multiple-position switch, and four resistors. The twenty volt battery and a five ohm resistor are in series with point T between them. The switch is in series with the battery, point T and the five ohm resistor. The switch can be connected to one of three points W, X, and Y to complete the circuit. If the switch is connected to point Y, a twelve ohm resistor and point U is in the series circuit. If the switch is connected to point X, a five ohm resistor but not point U is in the series circuit. If the switch is connected to point W, a three ohm resistor but not point U is in the series circuit.
  1. Calculate the current generated in the blanket when the switch is connected to point X. Show your calculations and include units in your answer.
  1. Calculate the power generated in the blanket when the switch is connected to point X. Show your calculations and include units in your answer.
  1. Explain why a fuse at point T would be more effective in this circuit than a fuse at point U.
  1. Identify which point the switch should be connected to in order to generate the most warmth. Explain your answer.

Scoring Guide and Sample Student Work
Select a score point in the table below to view the sample student response.

ScoreDescription
4 The response demonstrates a thorough understanding of current, power, and the arrangements of electrical components in series circuits. The response correctly calculates the current and power generated by the blanket when the switch is connected to point X. The response also clearly explains why a fuse at point T would be more effective than a fuse at point U, and correctly identifies and clearly explains which switch point will generate the most warmth.
4
3 The response demonstrates a general understanding of current, power, and the arrangements of electrical components in series circuits.
2 The response demonstrates a limited understanding of current, power, and the arrangements of electrical components in series circuits.
1 The response demonstrates a minimal understanding of current, power, and the arrangements of electrical components in series circuits.
0 The response is incorrect or contains some correct work that is irrelevant to the skill or concept being measured.

Note: There are 2 sample student responses for Score Point 4.

High School Intro Physics

Question 12: Electromagnetism
Question 23: Motion and Forces
Question 32: Motion and Forces
Question 44: Heat and Heat Transfer
Question 45: Waves and Radiation

Return to the MCAS 2015 Student Work Directory



Last Updated: August 21, 2017
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