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Pathways to Astronomy

Stephen E. Schneider

Chapter 21

Light, Matter, and Energy - all with Video Answers

Educators

Chapter Questions

00:48

Problem 1

Given that the Sun is 150 million kilometers from the Earth, calculate how long it takes light to travel from the Earth to the Sun.

Khoobchandra Agrawal
Khoobchandra Agrawal
Numerade Educator
02:04

Problem 2

Suppose you are operating a remote-controlled spacecraft on Mars from a station here on Earth. How long will it take the craft to respond to your command if Mars is at its nearest point to Earth? (You will need to look up a few numbers in the Appendix.)

Mayukh Banik
Mayukh Banik
Numerade Educator
02:40

Problem 3

a. At Mars's distance of $1.52 \mathrm{AU}$ from the Sun, how many times less bright is the light from the Sun than at Earth's distance?
b. What about at Mercury's distance of 0.39 AU?

Ajay Singhal
Ajay Singhal
Numerade Educator
02:51

Problem 4

The Sun is about 10 billion times brighter than the next brightest star, Sirius, (as seen from Earth). How far would we have to be from the Sun for the Sun to be as bright as Sirius? (The distance from the Earth to the Sun is $1.00 \mathrm{AU}$ ).

Ma Ednelyn Lim
Ma Ednelyn Lim
Numerade Educator
02:07

Problem 5

Suppose that the electron in a hydrogen atom is in the fourth energy level (the third excited state). How many differentenergy photons can be released as the electron drops back to the ground state?

James Irizarry
James Irizarry
Numerade Educator
01:30

Problem 6

Describe, using basic principles, the story of a green photon that was generated in the Sun, was reflected off some object on Earth, and then entered your eye. What happened at the atomic level along each step of its journey? For example, what does it mean that you "see" the photon?

Abigail Schammel
Abigail Schammel
Numerade Educator