We are open Saturday and Sunday!

Call Now to Set Up Tutoring:

(888) 888-0446

MCAT Physical : Thin Lens Equation

Study concepts, example questions & explanations for MCAT Physical

Create An Account

All MCAT Physical Resources

8 Diagnostic Tests 303 Practice Tests Question of the Day Flashcards Learn by Concept

Example Questions

Example Question #4 : Gre Subject Test: Physics

A virtual image is formed $\small 8cm$ from a convex mirror with a focal length of $\small 10cm$ . How far from the mirror is the object that created this image?

Possible Answers:

4.4cm

40cm

2.5cm

22.5cm

2cm

Correct answer:

40cm

Explanation:

Use the equation:

$\frac{1}{f}=\frac{1}{d_i}+\frac{1}{d_o}$

Focal length is negative for convex mirrors, and image distance is negative for virtual images. We are given these values in the question, allowing us to calculate the object distance.

$\frac{1}{-10}=\frac{1}{-8}+\frac{1}{d_o}$

$\frac{1}{d_o}=\frac{1}{40}$

$d_{o}= 40cm$

Report an Error

Example Question #1 : Thin Lens Equation

How far from a converging lens must an object be placed to produce an image that is NOT real and inverted? Given the answer as d_o in terms of the focal length, .

Possible Answers:

d_o >2f

f<d_o<2f

d_o=2f

d_o=f

Correct answer:

d_o=f

Explanation:

When an object is placed a distance from a converging lens or mirror that is equal to the focal length, no image is produced. To test this out, stand in front of a single concave mirror and continue to back up until you no longer see an image. Once you've reached this point, you will be standing one focal length away from the mirror.

When the object is less than one focal length away from the converging lens/mirror, the image will be virtual and upright.

If you don't have these trends committed to memory, you can derive them from the equation $\frac{1}{d_o} + \frac{1}{d_i} = \frac{1}{f}$ .

When d_i is a negative integer the image is virtual, and when it is a positive integer the image is real.

Report an Error

Example Question #1 : Thin Lens Equation

A certain farsighted person cannot focus on objects closer to his eyes than $\small 140cm$ . What focal length eyeglass lenses are needed in order to focus on a newspaper held at $\small 35cm$ from the person's eyes, if the glasses are worn $\small 2cm$ from his eyes?

Possible Answers:

2cm

27cm

47cm

43cm

28cm

Correct answer:

43cm

Explanation:

First we need the object and image distances away from the eyeglass lenses. Here, the newspaper is the object and the $\small 140cm$ focal point is where the image needs to be located. Find the distance from the object to the lens, and the distance of the image to the lens, by subtracting out the distance from the lens to the eye.

$d_{ol}=d_{oe}-d_{le}=35cm-2cm=33cm$

$d_{il}=d_{ie}-d_{le}=140cm-2cm=138cm$

Now apply the thin lens equation to determine focal length.

$\frac{1}{f} = \frac{1}{d_{i}}+\frac{1}{d_{o}}$

Recall that if the image is on the same side of the lens as the object, then image distance is negative.

$\frac{1}{f}=\frac{1}{-138}+\frac{1}{33}\approx0.023$

$f = \frac{1}{0.023}\approx 43cm$

Report an Error

Example Question #1 : Thin Lens Equation

An object is placed 50cm in front of a concave mirror of radius 60cm. How far from the mirror is the image?

Possible Answers:

120cm

300cm

75cm

60cm

20cm

Correct answer:

75cm

Explanation:

Relevant equations:

r = 2f

$\frac{1}{f}=\frac{1}{d_o}+\frac{1}{d_i}$

Step 1: Find the focal length of the mirror.

$r = 2f \rightarrow f = \frac{r}{2}=\frac{60cm}{2}=30cm$

Step 2: Plug this focal length and the object distance into the lens equation.

$\frac{1}{30}=\frac{1}{50}+\frac{1}{d_i}$

d_i = 75cm

Report an Error

Example Question #5 : Thin Lens Equation

An object that is 3cm tall is placed 30cm from a convex spherical mirror of radius 40cm, along its central axis. What is the height of the image that is formed?

Possible Answers:

1.7cm

7.5cm

12.0cm

1.2cm

6.0cm

Correct answer:

1.2cm

Explanation:

Relevant equations:

r = 2f

$\frac{1}{f}= \frac{1}{d_i}+ \frac{1}{d_o}$

$M = -\frac{d_i}{d_o}= \frac{h_i}{h_o}$

Step 1: Find the focal length of the mirror (remembering that convex mirrors have negative focal lengths, by convention).

$r = 2f \rightarrow f = \frac{r}{2}= \frac{40cm}{2}=20cm \rightarrow -20cm$

Step 2: Find the image distance using the thin lens equation.

$\frac{1}{-20}=\frac{1}{30}+\frac{1}{d_i}$

d_i = -12cm

Step 3: Use the magnification equation to relate the object distances and heights.

$-\left (\frac{-12cm}{30cm} \right )= \frac{h_i}{3cm}$

h_i = 1.2cm

Report an Error

View MCAT Chemical and Physical Foundations of Biological Systems Tutors

Joseph
Certified Tutor

Rutgers University-New Brunswick, Bachelor in Arts, Chemistry. Rutgers Graduate School of Biomedical Sciences, Current Grad S...

View MCAT Chemical and Physical Foundations of Biological Systems Tutors

Denisha
Certified Tutor

Nova Southeastern University, Doctor of Medicine, Ayurvedic Medicine. Nova Southeastern University, Master in Public Health, ...

View MCAT Chemical and Physical Foundations of Biological Systems Tutors

Christy
Certified Tutor

Northern Michigan University, Bachelor in Arts, Graphic Design. Northern Michigan University, Bachelor of Science, Premedicine.

All MCAT Physical Resources

8 Diagnostic Tests 303 Practice Tests Question of the Day Flashcards Learn by Concept

Popular Subjects

Spanish Tutors in Seattle, Biology Tutors in Denver, Statistics Tutors in Atlanta, Biology Tutors in San Francisco-Bay Area, Physics Tutors in Denver, GMAT Tutors in Washington DC, Computer Science Tutors in San Francisco-Bay Area, Computer Science Tutors in Atlanta, SSAT Tutors in Philadelphia, ACT Tutors in Chicago

Popular Courses & Classes

SAT Courses & Classes in Seattle, GRE Courses & Classes in Washington DC, GMAT Courses & Classes in Washington DC, SAT Courses & Classes in Chicago, ACT Courses & Classes in Atlanta, Spanish Courses & Classes in Houston, GRE Courses & Classes in Phoenix, GMAT Courses & Classes in Seattle, SAT Courses & Classes in San Francisco-Bay Area, GRE Courses & Classes in San Francisco-Bay Area

Popular Test Prep

GRE Test Prep in Denver, ACT Test Prep in Atlanta, ACT Test Prep in Miami, SSAT Test Prep in Houston, MCAT Test Prep in Boston, SSAT Test Prep in New York City, GRE Test Prep in Phoenix, SAT Test Prep in San Diego, GRE Test Prep in Washington DC, ACT Test Prep in Chicago

DMCA Complaint

If you believe that content available by means of the Website (as defined in our Terms of Service) infringes one or more of your copyrights, please notify us by providing a written notice (“Infringement Notice”) containing the information described below to the designated agent listed below. If Varsity Tutors takes action in response to an Infringement Notice, it will make a good faith attempt to contact the party that made such content available by means of the most recent email address, if any, provided by such party to Varsity Tutors.

Your Infringement Notice may be forwarded to the party that made the content available or to third parties such as ChillingEffects.org.

Please be advised that you will be liable for damages (including costs and attorneys’ fees) if you materially misrepresent that a product or activity is infringing your copyrights. Thus, if you are not sure content located on or linked-to by the Website infringes your copyright, you should consider first contacting an attorney.

Please follow these steps to file a notice:

You must include the following:

A physical or electronic signature of the copyright owner or a person authorized to act on their behalf; An identification of the copyright claimed to have been infringed; A description of the nature and exact location of the content that you claim to infringe your copyright, in \ sufficient detail to permit Varsity Tutors to find and positively identify that content; for example we require a link to the specific question (not just the name of the question) that contains the content and a description of which specific portion of the question – an image, a link, the text, etc – your complaint refers to; Your name, address, telephone number and email address; and A statement by you: (a) that you believe in good faith that the use of the content that you claim to infringe your copyright is not authorized by law, or by the copyright owner or such owner’s agent; (b) that all of the information contained in your Infringement Notice is accurate, and (c) under penalty of perjury, that you are either the copyright owner or a person authorized to act on their behalf.

Send your complaint to our designated agent at:

Charles Cohn Varsity Tutors LLC
101 S. Hanley Rd, Suite 300
St. Louis, MO 63105

Or fill out the form below:

Do not fill in this field

Contact Information

* Full legal name

Company name

* Phone number

* Email address

Address

* Address1

Address2

* City

* State

* Zipcode

* Country

Complaint Details

* URL of copyrighted work (where your original material is located)

* Please describe the copyrighted work so that it may be easily identified

I am the owner, or an agent authorized to act on behalf of the owner of an exclusive right that is allegedly infringed.

I have a good faith belief that the use of the material in the manner complained of is not authorized by the copyright owner, its agent, or the law.

This notification is accurate.

I acknowledge that there may be adverse legal consequences for making false or bad faith allegations of copyright infringement by using this process.

* Signature (your digital signature is legally binding)

HIGH SCHOOL

GRADUATE SCHOOL

K-8

Search 50+ Tests

math tutoring

science tutoring

foreign languages

elementary tutoring

other

Search 350+ Subjects

MCAT Physical : Thin Lens Equation

Study concepts, example questions & explanations for MCAT Physical

All MCAT Physical Resources

Example Questions

Example Question #4 : Gre Subject Test: Physics

Example Question #1 : Thin Lens Equation

Example Question #1 : Thin Lens Equation

Example Question #1 : Thin Lens Equation

Example Question #5 : Thin Lens Equation

All MCAT Physical Resources

Report an issue with this question

DMCA Complaint

Contact Information

Address

Complaint Details

Email address:
Your name:
Feedback: