Current Exam Review

A transformer is a device used to increase or decrease the voltage through induction. Which fundamental force is responsible for this induction?

• Strong force

• Weak force

• Electromagnetic force

• Gravitational force

Tags

NGSS.HS-PS2-5

What is the force between two 1.5x10^-5C charges separated by 2.0m?

• 22,500N

• 44, 500N

• 0.506 N

• 2.022 N

Two charged spheres are 20 cm apart and exert an attractive force of 4 x 10^-9 N on each other. What will the force of attraction be when the spheres are moved to 10 cm apart?

• 1.6 x 10^-8N

• 3.2x10^-8N

• 4 x 10^-9N

• 2 x 10^-9N

What is needed in order to create a magnetic field?

• Atoms

• A bar of iron

• Electric charge

• A changing electric field

A material is most likely an insulator if the relative strength of the force attracting valence electrons to the nucleus of the atoms in the material is ―

• low

• high

• zero

• temperature dependent

Tags

NGSS.HS-PS1-3

A student connects a length of unknown material in series with a battery and an ammeter (which measures current flow). When the circuit is complete, the ammeter reads that no current is flowing. The unknown material is most likely ―

• a conductor

• an insulator

• a superconductor

• a semiconductor

Silicon is a substance often used in electronic devices. Silicon has a high electrical resistance compared to metals which means that it does not release its electrons very easily. However, it does conduct electricity when the right conditions are met. These properties allow electronic devices to control the electrical current sent through silicon much easier than a typical metal substance. The properties of silicon would cause it to best be classified as a —

• conductor

• insulator

• semiconductor

• superconductor

A superconductor has a critical temperature below which ―

• it stops conducting

• it begins to conduct

• its resistance becomes zero

• its resistance becomes infinite

Which of the following, on average, has the highest electrical resistance value?

• Conductors

• Insulators

• Semiconductors

• Superconductors

A cell phone company is trying to improve their chargers so that the battery charges faster. Based on the information above, which material would be the best to use when making

the cell phone charger cable?

• Aluminum

• Copper

• Glass

• Water