Modern Physics Reading Questions

You do not need to print this page out. In your notebooks, list the numbered problems and answer the questions next to the appropriate numbers.

You may need to lookup given values from the Internet as you work through these problems.


A wire carries a current of 5 Amps for 1 minute. How many electrons pass through the wire during this time?(hint) pg 1
A photon does not have any mass. How does the photon's energy relate to its momentum? [proportionality] (hint) pg 1
A Helium atom has a mass of 6.6x10-27 kg. A helium atom consists of 2 protons, 2 neutrons, and 2 electrons. If the mass of 2 protons, 2 electrons, and 2 neutrons are added together, they do not equal the mass of one helium atom. The missing mass is called the mass defect. When this amount of mass is converted to energy, it called the binding energy -because it binds the nucleus together. What is the binding energy for helium? (hint) pg 1
A microwave oven is rated at 1200 W. The "Model S" Tesla can move from 0 to 60 mph in 3.1 seconds. Which uses up more energy, the microwave running for 5 minutes or the heaviest version of the Tesla Model S as it accelerates to 60 mph? (hint) pg 1
In an old style "fat box" CRT television, an electron gun is used to propel electrons to the rear of the television screen's glass face. The electron gun is energized by a 28,000 v flyback transformer that is connected to two parallel plates 1.0 cm apart. This provides the force to propel an electron. A CRT television fires about 30 electrons per second at one pixel on the television screen. It take 1.08 x10-7 seconds for an eletron to travel across the plates. How much power is used during 1.00 second to light up the one pixel, ...assuming the electrons start from rest? (hint) pg 1

Below is the label from a green laser pointer. What is the maximum number of photons emitted by the laser pointer per second? (hint) pg 1

Image: Sky and Telescope, accessed on 4/12/2016,

What is the approximate energy level, in eV's, of one photon from a infrared, green, and UV laser pointer? (hint) pg 1

by Tony Wayne ...(If you are a teacher, please feel free to use these resources in your teaching.)

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