Massachusetts Comprehensive Assessment System

2019, High School Intro Physics

Question 45: Open-Response

Reporting Category: Electromagnetism
Standard: 5.3 - Analyze simple arrangements of electrical components in both series and parallel circuits. Recognize symbols and understand the functions of common circuit elements (battery, connecting wire, switch, fuse, resistance) in a schematic diagram.
Standard: Sci.HS.PHY.2.09 - Evaluate simple series and parallel circuits to predict changes to voltage, current, or resistance when simple changes are made to a circuit. Clarification Statements: Predictions of changes can be represented numerically, graphically, or algebraically using Ohm’s law. Simple changes to a circuit may include adding a component, changing the resistance of a load, and adding a parallel path, in circuits with batteries and common loads. Simple circuits can be represented in schematic diagrams. State Assessment Boundary: Use of measurement devices and predictions of changes in power are not expected in state assessment.

Two circuits, W and X, are shown in the diagrams.

Circuit X has the same total resistance as circuit W, but circuit X has only one resistor, R₄.

a. Calculate the resistance of R₄. Show your calculations and include units in your answer.

b. Calculate the current through R₄. Show your calculations and include units in your answer.

Another circuit, Y, has the same battery and resistor as circuit X but also has another resistor, R₅, as shown.

c. Determine whether adding R₅ increases or decreases the total current in circuit Y. Explain your reasoning.

d. In your Student Answer Booklet, copy circuit Y. On your circuit, add a third resistor labeled “R_new” in a location that will not change the current through R₄.

Scoring Guide for Idea Development

Select a score point in the table below to view the sample student response.

Score	Description
4	The response demonstrates a thorough understanding of Ohm's law and how to analyze simple series and parallel circuits. The response correctly determines the resistance of a resistor and correctly calculates the current through that resistor. The response correctly identifies the effect of adding a resistor to a circuit in parallel and clearly explains the reasoning. The response also correctly includes a circuit with a resistor added to a correct location.
4
3	The response demonstrates a general understanding of Ohm's law and how to analyze simple series and parallel circuits.
2	The response demonstrates a limited understanding of Ohm's law and how to analyze simple series and parallel circuits.
1	The response demonstrates a minimal understanding of Ohm's law and how to analyze simple series and parallel 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: Waves and Radiation

Question 23: Motion and Forces

Question 32: Motion and Forces

Question 44: Heat and Heat Transfer

Question 45: Electromagnetism

Return to the MCAS 2019 Student Work Directory

Last Updated: May 5, 2020