Unit 7 Practice Test

Mark learned about electrical circuits at school and wanted to build one at home. He used the circuit shown in the diagram. However, none of the lights were glowing. He discovered that the current did not flow due to a broken filament in one of the bulbs. Which of the following correctly identifies the series circuit which can be used to replace Mark's broken lights?

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You are asked to verify the statement “for a constant current, there is a direct relationship between voltage and resistance”. Which of the following calculations could you perform to complete this task?

• An initial resistance of 50 Ω allows a current of 2.6 A. When the resistance is doubled, the current is 2.6 A.

• An initial voltage of 25.0 V creates a current of 1.25 A. The voltage is decreased to 12.5 V to create a current of 0.625 A.

• An initial resistance of 30 Ω allows a current of 1.25 A to flow. When the resistance is doubled, the current is 0.625 A.

• An initial current of 2.6 A is created when 62.5 V occurs. The current is then doubled to 5.2 A and the voltage doubles to 125 V.

A student creates an electric circuit model containing identical light bulbs. Which light bulbs MUST be unscrewed to stop the flow of current in the whole circuit and why?

• Light bulb P because it is connected by a series connection.

• Light bulb O because it is connected by a series connection.

• Light bulb M because it is connected by a parallel connection.

• Light bulbs M and N because they are connected in parallel connections.

Tags

NGSS.MS-PS2-3

Henry investigates how the flow of electricity produces magnetism. He follows this procedure. Since only two paper clips adhered to the nail, which action would BEST make the electromagnet attract more paper clips?

• Replace the nail with a pencil.

• Increase the number of coils of insulated wire.

• Connect an on/off switch between the battery and the nail.

• Reverse the direction of the positive and negative poles of the battery.

Tags

NGSS.MS-PS2-3

A student created a simple motor using a D battery, a magnet, two paper clips, a rubber band, and some insulated wire. The coil loop in the center spins freely. What do you predict would happen to the spinning loop if the magnet is flipped upside down so that the south and north poles are inverted?

• The spinning loop will not spin anymore.

• The speed of the spinning loop will increase.

• The spinning loop will be repelled by the magnet.

• The spinning loop will change the direction it spins.

Tags

NGSS.MS-PS2-5

A student takes a coil of wire along with two metal rods and places them as shown in Figure 1 and Figure 2. The student connects the coil to a direct current supply as shown in Figure 1 and records his observation. The student then connects the coil to an alternating current supply as shown in Figure 2 and notes down his observation. Which of the choices BEST describes the student’s observations?

• When the alternating current (AC) is passed, the student notices that the metal rods attract, and when direct current (DC) is passed the metal rods remain unchanged.

• When the direct current (DC) is passed, the student notices that the metal rods remain unchanged, and when alternating current (AC) is passed, the metal rods are repelled.

• When the alternating and direct current (AC) is passed, the student notices that the metal rods remain unchanged

• When the direct current (DC) is passed, the student notices that the metal rods are magnetized and moved apart and when alternating current (AC) is passed, the metal rods remain unchanged.

Tags

NGSS.MS-PS2-5

The diagram shows four different circuits. Which circuit will stop producing light if one bulb burns out?

• Circuit 1

• Circuit 2

• Circuit 3

• Circuit 4

Read the passage below and answer the question(s) that follow. RPM of Toy Motor Using Different Voltages Eliana has a toy motor that she is testing using different voltages. She records the speed of the motor each time in revolutions per minute, or rpm. She uses the data to make the graph shown. What is the most significant cause of the motor's spin?

• the force of the current in the wire

• the force of the electromagnetic field

• the movement of the air flowing around the motor

• the movement of the battery attached to the motor

Tags

NGSS.MS-PS2-2

What is described as a series circuit that is used to produce a lower voltage from a higher voltage battery?

• short circuit

• series divider

• parallel circuit

• voltage divider

Noel is trying to understand the relationship between electron flow and the polarity of an electromagnet. He wants to test the electromagnet he created, shown in the diagram. First, Noel needs to know which direction electrons flow through the copper wire. Which statement about the flow of electrons is correct?

• Electrons flow from north to south because of Earth's magnetic field.

• Electrons flow from south to north because of Earth's magnetic field.

• Electrons flow from the positive terminal of a battery to the negative terminal of a battery.

• Electrons flow from the negative terminal of a battery to the positive terminal of a battery.

Tags

NGSS.HS-PS2-5

NGSS.HS-PS3-5