Multiple Choice Question

Question

A student is designing an investigation of the distribution of charges in conductors. She will use two conducting spheres mounted on insulating stands in the investigation. The conducting spheres are shown.

image 20dd73ed8cf143748d14ec76f16d7970

The student wants to separate the charges of the spheres as shown.

image 6e01081a67464a9cb75abfdb169f19b8

What should the student do in her investigation to produce these results?

A.
She should place a negatively charged rod near the left sphere.

B.
She should place a positively charged rod near the left sphere.

C.
She should place two negatively charged rods near each sphere.

D.
She should place two positively charged rods near each sphere.

Answer 1

To achieve the desired separation of charges in the conducting spheres, the student should use a method that induces charge separation through electrostatic induction.

When a negatively charged rod is brought near the left sphere, it will cause the electrons in that sphere to be repelled, resulting in a positive charge on the side closest to the rod and a negative charge on the side farthest from the rod. Consequently, if the right sphere is neutral and initially in contact or very close, it can become negatively charged due to the movement of electrons towards it.

Thus, the correct choice for the student to produce the desired charge distribution is:

A. She should place a negatively charged rod near the left sphere.

Answer 2

Passage 12472
Directions: Read the passage about the factors that affect the magnetism of electromagnets.

An electromagnet consists of an insulated copper wire wound around an iron core and connected to a source of electricity. The magnetism of electromagnets disappears when the electricity is turned off. A student performs two experiments to study the factors that affect the magnetism produced by an electromagnet.

Experiment 1

He prepares an electromagnet by wrapping ten coils of a wire around an iron nail. The wire is then connected to a 4.5-volt battery. Next, the electromagnet is placed close to evenly spread iron paper clip

He records the number of paper clips that are attracted to the magnet in a table, repeating the activity with different numbers of coils around the nail.

Number of coils Number of paper clips attracted to the magnet
10 6
15 11
20 17
25 23
Experiment 2

In his second experiment, he repeats the same procedure he used in Experiment 1, except that this time he keeps the number of coils the same but changes the battery voltage. He records the number of paper clips attracted each time in a second table.

Battery Voltage (V) Number of paper clips attracted to the magnet
3.0 3
4.5 6
6.0 9
7.5 13
Multiple Choice Question
Which question can be answered based on the results of Experiment 2?

A.
How does the strength of an electromagnet vary when the voltage of the power source changes?

B.
How does the strength of an electromagnet vary when the number of paper clips changes?

C.
How does the voltage of an electromagnet vary when the strength of the paper clips changes?

D.
How does the voltage of an electromagnet vary when the number of coils of wire changes?

Answer 3

The results of Experiment 2 focus specifically on the relationship between the battery voltage and the number of paper clips attracted to the electromagnet while keeping the number of coils constant. Therefore, the question that can be answered based on the results of Experiment 2 is:

A. How does the strength of an electromagnet vary when the voltage of the power source changes?

This option directly relates to the data collected in Experiment 2, which measures the attraction of paper clips against different battery voltages.

Answer 4

Multiple Choice Question
A student wishes to make the magnetic force exerted by the electromagnet shown below greater.

image e0200808b8fa436fae6f573f2546fa05

Which procedure step could the student follow to accomplish this goal?

A.
increase the length of wire at location 1

B.
open the switch at location 2

C.
add more batteries in series at location 3

D.
reduce the number of wire turns at location 4

Answer 5

To increase the magnetic force exerted by an electromagnet, generally, one would seek to increase the current flowing through the wire or the number of coils of wire around the core.

Looking at the options:

• A. Increase the length of wire at location 1 – This step alone may not necessarily increase the magnetic force significantly, as it does not directly relate to increasing the number of turns or the current through the wire.

• B. Open the switch at location 2 – This would deactivate the electromagnet, causing the magnetic force to disappear, which is not what the student wants.

• C. Add more batteries in series at location 3 – This would increase the voltage supplied to the electromagnet, thereby increasing the current flowing through the wire, which in turn increases the magnetic force.

• D. Reduce the number of wire turns at location 4 – This would decrease the magnetic force, as fewer turns generally result in a weaker magnet.

Given these considerations, the best option for increasing the magnetic force exerted by the electromagnet is:

C. Add more batteries in series at location 3.

Answer 6

Multiple Select Question
A student places a drop of purple food coloring into one beaker of water at 20°C and another drop into another beaker of water at 50°C. The temperature of the food coloring is 19°C. The picture shows what he observes.

What explains what the student observes in this investigation? Select all that apply.
A.
The food coloring moves faster in hot water.

B.
The food coloring moves slower in hot water.

C.
The food coloring is denser than the cold water.

D.
The food coloring is less dense than the cold water.

E.
The food coloring separates into two different colors.

F.
The food coloring increases the temperature of the water.

Answer 7

In this investigation, the student observes the behavior of food coloring in water at different temperatures. The key points to consider are how temperature affects the movement of molecules in the water and the behavior of the food coloring.

1. A. The food coloring moves faster in hot water. – This is true. In hotter water (50°C), the water molecules are moving faster, which helps disperse the food coloring more quickly.

2. B. The food coloring moves slower in hot water. – This is false. The food coloring does not move slower in hot water; it actually moves faster due to the increased kinetic energy of the water molecules.

3. C. The food coloring is denser than the cold water. – This is generally not a correct assumption. Most food colorings are not denser than water, especially when mixed.

4. D. The food coloring is less dense than the cold water. – This is often true, as many food colorings are designed to mix well with water, which can indicate they are not denser.

5. E. The food coloring separates into two different colors. – This is usually not applicable unless specific types of coloring are used that can separate based on interaction with different temperatures, which is not generally the case for standard food colorings.

6. F. The food coloring increases the temperature of the water. – This is false. The food coloring does not significantly affect the temperature of the water.

Based on this analysis, the correct selections that explain what the student observes in this investigation would be:

A. The food coloring moves faster in hot water.
D. The food coloring is less dense than the cold water.

Answer 8

Multiple Select Question
A ball rolls down a grassy hill and eventually comes to a stop. Select three of the reasons the ball comes to a stop.
A.
Friction and drag oppose the motion of the ball.

B.
There is no force acting to move the ball forward.

C.
The force of friction against the ball is decreased.

D.
The forces opposing the ball are unbalanced.

E.
The force of gravity has increased and stopped the ball.

F.
There was too much inertia to keep the ball rolling.

Answer 9

When a ball rolls down a grassy hill and eventually comes to a stop, several factors contribute to the cessation of its motion. Let's analyze the options:

1. A. Friction and drag oppose the motion of the ball. – This is true. Friction from the grass and air resistance (drag) slow down the ball and eventually stop it.

2. B. There is no force acting to move the ball forward. – This is also true. Once the ball is no longer on an incline (or if it slows down too much), there is indeed no net force propelling it forward.

3. C. The force of friction against the ball is decreased. – This is false. In fact, the frictional force remains or increases as the ball slows down, contributing to its eventual stop.

4. D. The forces opposing the ball are unbalanced. – This is true. The friction and drag forces are greater than the gravitational force pulling the ball down the hill once the ball slows enough. This unbalance leads to a net force acting in the opposite direction to the ball's motion, causing it to stop.

5. E. The force of gravity has increased and stopped the ball. – This is false. The force of gravity remains constant; it does not increase in a way that would stop the ball. Gravity is always acting downward, but it is counteracted by the frictional forces.

6. F. There was too much inertia to keep the ball rolling. – This is somewhat misleading. Inertia is the resistance to change in motion, but the ball does not have "too much" inertia; rather, it has enough inertia to continue moving until acted upon by opposing forces (friction and drag).

Based on this analysis, the three correct answers to explain why the ball comes to a stop are:

A. Friction and drag oppose the motion of the ball.
B. There is no force acting to move the ball forward.
D. The forces opposing the ball are unbalanced.

Answer 10

Multiple Select Question
A student built a simple electromagnet with copper wire, an iron bolt, and a 1.5-volt battery. The electromagnet was able to lift a paper clip from 3 centimeters away. Select three ways the student can increase the strength of his electromagnet.
A.
He can use a thicker piece of copper wire.

B.
He can reverse the orientation of the battery.

C.
He can replace the iron bolt with a wooden rod.

D.
He can add a switch between the battery and the iron bolt.

E.
He can replace the 1.5-volt battery with a battery of higher voltage.

F.
He can use a longer piece of wire that wraps more times around the bolt.

Answer 11

To increase the strength of an electromagnet, a student can take several actions based on the principles of electromagnetism. Here’s an analysis of the options provided:

1. A. He can use a thicker piece of copper wire. – This is generally not the most effective method for increasing the strength of the electromagnet since thicker wire has lower resistance, but it does not significantly increase the magnetic field strength produced by the wire.

2. B. He can reverse the orientation of the battery. – This will not increase the strength of the electromagnet; it will just reverse the direction of the magnetic field.

3. C. He can replace the iron bolt with a wooden rod. – This is incorrect. Replacing the iron bolt with a wooden rod would decrease the strength of the electromagnet, as wood is not ferromagnetic and would not enhance the magnetic field.

4. D. He can add a switch between the battery and the iron bolt. – Adding a switch would not inherently increase the strength of the electromagnet. It simply allows the student to turn the electromagnet on or off.

5. E. He can replace the 1.5-volt battery with a battery of higher voltage. – This is correct. A higher voltage battery would provide more current through the wire, which would strengthen the magnetic field of the electromagnet.

6. F. He can use a longer piece of wire that wraps more times around the bolt. – This is also correct. Increasing the number of turns in the wire around the iron bolt increases the magnetic field strength as the field is proportional to the number of wire coils.

Thus, the three methods the student can employ to increase the strength of his electromagnet are:

E. He can replace the 1.5-volt battery with a battery of higher voltage.
F. He can use a longer piece of wire that wraps more times around the bolt.
(Note: Option A does not increase strength; the correct answers are E and F, with no additive method to choose from the provided options.)