Category Archives: High School

Items appropriate for use in a high school physics course.

A2L Item 261

Goal: Recognize a lack of information

Source: CT151.2S02-24

Consider the situations at right. Let m < M. Which spring has
the largest spring constant?

  1. A
  2. B
  3. C
  4. A and B are equal
  5. A and C are equal
  6. B and C are equal
  7. All of them have the same spring constant
  8. Cannot be determined

Commentary:

Answer

(8) The objective of this question is to reveal what students are
assuming about the springs. The reasoning behind any incorrect answer
should be thoroughly discussed.

A2L Item 258

Goal: Hone the concept of average velocity

Source: CTtil2;12;02

While traveling from Boston to Hartford, Person A drives at a constant
speed of 55 mph for the entire trip. Person B drives at 65 mph for half
the trip and then drives 45 mph for the second half of the trip. When
would B arrive in Hartford relative to A?

  1. B arrives before A.
  2. B arrives at the same time as A.
  3. B arrives after A.
  4. Not enough information.

Commentary:

Answer

(3) Many students are inclined to average the speeds and conclude that
they arrive at the same time. It is often useful to compare this
situation to the one in which time is halved.

A2L Item 259

Goal: Interrelate representations of kinematical quantities

Source: CT151.2-8

An object’s motion is described by the graph above. The position of the
object at t = 9 seconds is most nearly…

  1. 0 meters
  2. 200 meters
  3. 300 meters
  4. 400 meters
  5. 500 meters
  6. Cannot be determined

Commentary:

Answer

(6) This problem is primarily to determine if students appreciate the
information available from a graph. Many students will determine the
displacement forgetting that the initial position is unknown.

A2L Item 256

Goal: Hone the vector nature of the electric field

Source: CTQ283-6

Four charges are positioned as
shown. What is the direction of the electrical field at the origin?

  1. Along i or in the +x direction
  2. Along -i or in the -x direction
  3. Along j or in the +y direction
  4. Along -j or in the -y direction
  5. Along some other direction
  6. E=0 at the origin

Commentary:

Answer

(6) Difficulty with this question usually indicates that students are
not familiar with vectors. Good follow up question: ask whether it
matters if the charges are along a 45 degree line.

A2L Item 257

Goal: Hone the vector nature of the electric field

Source: CTQ283-7

Four
charges are positioned as shown. What is the direction of the
electrical field at the origin?

  1. Along i or in the +x direction
  2. Along -j or in the -y direction
  3. Along j or in the +y direction
  4. Along -i or in the -x direction
  5. Along some other direction
  6. E=0 at the origin

Commentary:

Answer

(3) Difficulty with this question indicates that students do not know
how the direction of the electric field relates to the sign of the
charge.

A2L Item 255

Goal: Hone the vector nature of the electric field

Source: CTQ283-5

Four
charges are positioned as shown. What is the direction of the
electrical field at the origin?

  1. Along i or in the +x direction
  2. Along j or in the +y direction
  3. Along -i or in the -x direction
  4. Along -j or in the -y direction
  5. Along some other direction
  6. E=0 at the origin

Commentary:

Answer

(6) Difficulty with this question usually indicates that students are
not familiar with vectors. Good follow up questions are to change the
sign of one or more charges.

A2L Item 247

Goal: Link energy with electrical quantities

Source: 283 – energy in capacitor

Consider the following circuit. The capacitor is uncharged when switch S
is closed at t = 0. After current stops flowing and the capacitor is
fully charged the energy stored in the capacitor is:

  1. V^2^/R
  2. CE^2^/2
  3. QV/2
  4. V/RC
  5. none of the above

Commentary:

Answer

(3) The intent of this question is to provide students the opportunity
to distinguish a correct but uncommon form for the stored energy from a
number of other familiar forms.

A2L Item 248

Goal: Link energy with electrical quantities

Source: 283-energy in L

Consider the following circuit. The switch S is closed at t = 0.
After a long time the energy stored in the inductor is:

  1. L^2^/R

  2. RL^2^/2

  3. LV/2R

  4. V/RL

  5. none of the above

Commentary:

Answer

(5) This is a good time to discuss with students the general form of
energy expressions as 1/2 something times (something else)^2^.

A2L Item 244

Goal: Hone skill at using Lenz’s Law

Source: 283-CTQsas36

Consider the four situations below in which a wire loop lies in the
plane of a long wire. In which case(s) is the induced current in the
loop in the counterclockwise direction? [Note: if no velocity is
indicated, the loop is stationary.]

  1. A only
  2. B only
  3. C only
  4. D only
  5. A and B
  6. C and D
  7. All cases.
  8. None of the above.

Commentary:

Answer

  1. Discussing each of the cases is valuable. Students have difficulty
    recognizing that the induced current is in a direction that causes the
    field of the induced current to compensate for the change in flux. Even
    when they nominally understand that, they have trouble reliably applying
    the right hand rule.

A2L Item 240

Goal: Reason regarding power in a circuit

Source: 283 circuit powers

Consider the circuit below. Which resistor has the greatest power
consumption?

  1. The 50Ω resistor
  2. The 10Ω resistor
  3. The 1000Ω resistor
  4. The 50Ω and 10Ω resistors
  5. The 50Ω and 1000Ω resistors
  6. The 10Ω and 1000Ω resistors
  7. All have the same power.

Commentary:

Answer

(1) The potential drop over the 10Ω and 1000Ω resistors is the same.
Since power goes as V^2^/R, more power is consumed in the 10Ω resistor
than the 1000Ω resistor. Further, since power also goes as I^2^R and only
a fraction of the current through the 50Ω resistor flows through the 10Ω
resistor, the 50Ω resistor must dissipate the most energy.