PH 202

Quiz # 10 (10 pts)

Name

Solution

 

A person whose near point is found to be  is using a simple magnifying lens and creates a magnification of .  How far from the object is the magnifying lens?

 

A.

B.

C.

 

D.

 

 

Solve for

 

 

 

So Correct Answer is D !

 

A telescope has an object lens with a focal length of 85.0 cm.  You want to set it up to measure an angular magnification of .  How far apart will you place the eye piece lens from the objective lens?

 

A.

B.

C.

 

D.

 

 

Two equations we need:

 

And

 

Using magnification equation we can find focal length of eye piece. 

 

So length is

 

So Correct Answer is A !

 

Two loud speakers are located  apart and are playing an in phase tone of  which under conditions of a nominal speed of sound of  has a wavelength of .  How far from the left speaker would you need to stand to hear the tones from the two speakers cancel out so that you would hear nothing?

 

A.

C.

 

 

 

 

B.

D.

 

Assume the distance we want from the left speaker is denoted as x.  The distance the sound travels from that speaker is of course also x.  The distance from the other speaker is .  So the difference in the path traveled by the tones can be written as:

 

 

For cancelation the path difference must be a half integer value of the wavelength

 

Solve for x

 

 

 

So Correct Answer is C !

 

In a Young’s double slit experiment being illuminated by a laser whose wavelength is  produces the 3rd bright fringe at an angle of .  What is the space between the two slits?

 

A.

C.

 

 

 

 

B.

D.

 

For bright fringes we have:

Solve for d

 

 

So the Correct Answer is B !

 

A pair of slits are separated by a distance of .  A greenish light of wavelength .  At what angle from the center of the interference pattern would you find the first dark fringe?

 

A.

C.

 

 

 

 

B.

D.

 

For dark fringes we have:

Solve for

 

As the first dark fringe is the m=0 one!

 

 

 

 

So Correct answer is A !

 

 

 

Please send any comments or questions about this page to ddonovan@nmu.edu

This page last updated on November 13, 2020