Electricity and Magnetism

What will increase the strength of the electromagnet?

• Removing the iron nail from the coil of wire.

• Decreasing the number of turns in the wire coil.

• Increasing the diameter of the turns in the coiled wire.

• Increasing the electric current flowing through the coiled wire.

Tags

NGSS.HS-PS2-5

NGSS.HS-PS3-5

Which equation correctly relates the current to the voltage in a simple circuit?

• I = RV

• I = V/R
  

• I = R/V

• I = R + V

Which model depicts a circuit that might carry items of varying loads (such as a hair dryer, a lamp, and a television) such that if any item is turned off, the others will still operate?

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Jonathan models two kinds of circuits containing identical bulbs and batteries. If one of the bulbs in each circuit breaks, which of the following explains what would happen to the rest of the bulbs?  

• Electrons would stop flowing in all bulbs of circuits A and B.

• The flow of electrons would stop in all bulbs of circuit A but not of circuit B.

• The flow of electrons would stop in all bulbs of circuit B but not of circuit A.

• Electrons would stop flowing only in the broken bulbs of circuits A and B.

Generators, like the one pictured, are used to produce electricity. What is the purpose of the magnets in the generator?

• The magnets attract protons in the wire coil.

• The magnets store the electricity produced by the generator.

• The magnets produce a changing magnetic field around the wire coil.

• The magnets provide the electrons necessary for the wire to produce a current.

Tags

NGSS.HS-PS2-5

A group of students were studying electromagnets. They wanted to explore the effect that the iron core had on the strength of the magnet. To test the strength, the students counted the number of paperclips the electromagnet could pick up with the same length of wire wrapped around a 0.5 cm core and around a 1 cm core. To their surprise, the electromagnet they made using the larger iron core picked up fewer paperclips. Which of the following statements CORRECTLY explains the students' observation that the larger iron core made a weaker electromagnet?

• Increasing the diameter of the iron core decreases the number of times the wire can be coiled around the core, which decreases the strength of the electromagnet.

• Increasing the diameter of the core increases the number of times the wire can be coiled around the core,  which will increase the strength of the electromagnet.

• Increasing the diameter of the core increases the number of times the wire can be coiled around the core, which will decrease the strength of the electromagnet.

• Increasing the diameter of the core decreases the number of times the wire can be coiled around the core, which will increase the strength of the electromagnet.

Tags

NGSS.HS-PS2-5

A flashlight bulb with a resistance of 20 ohms requires a potential difference of 6 volts across the terminals of the flashlight batteries in order to burn at a required brightness as shown. Flowing current that is higher than normal is referred to as overload. How much current would not be considered an overload? 

• 0.3A

• 3.33A

• 26A

• 120A

A student wraps a copper wire around a nail and then connects the wire to a battery. Which statement describes the role of the nail in this set-up?

• The nail is an electromagnet. The current in the wire induces a magnetic field from the nail.

• The nail is a permanent magnet. The current in the wire induces a magnetic field from the nail.

• The nail is an electromagnet. The magnetic field from the nail induces an electric current in the wire.

• The nail is a permanent magnet. The magnetic field from the nail induces an electric current in the wire.

Tags

NGSS.HS-PS2-5

In order to determine the current in a series circuit, first determine the equivalent resistance by calculating the sum of the resistances and then use the formula ​I=VRI=VR. The current in this series circuit is 0.5 A. What will the current be if the voltage is increased to 12 V?

• 0.63 A

• 0.67 A

• 1.5 A

• 7.6 A

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.HS-PS2-5