PHYS 1402 Lab: Thin Lenses and Spherical Mirrors

Name: _______________________________

Objectives

• To demonstrate the formation of images from convex and concave lenses.
• To identify the type of image formed by convex and concave lenses.
• To identify the type of image formed by concave mirror.

Key Terms

1. Converging (or convex lens): lens in which light rays that enter it parallel converge into a single point on the opposite side.
2. Diverging (or concave lens): lens that causes light rays to bend away from its optical axis.
3. Focal Point F: for a converging lens or mirror, the point at which converging light rays cross; for a diverging lens or mirror, the point from which diverging light rays appear to originate.
4. Focal length f: distance along the optical axis from the focal point to the Lens (or Mirror) that focuses the light rays.
5. Object distance d₀: distance between the object and lens (or mirror).
6. Image distance d_i: distance between the image formed and lens (or mirror).
7. Magnification . If m > 1, then image is enlarged; if m

Convex lens

1. Open Geometric Optics
2. Take some time to play with the simulation to get familiar with how it works.
3. Maximize your screen.
4. In this lab, you will be moving the object to analyze how images are formed. When you are ready to get started, be sure that your settings are as follows:

1. Select Principal Rays
2. Check the box: Focal points (F)
3. Check the box: Virtual Image

1. Use the ruler in the PhET program to measure the distances and height.
2. Using the ruler, measure the distance from to the center of lens.
3. Record this value as f below: Double this value and record as 2f.

f = _______________

2f = _______________

1. Measure the height of object (h_o) using the vertical ruler and record.

Just measure the height of the pencil or penguin. Do not include the height of frame in your measurement.

h_o = ________

1. Place the pencil beyond 2f. Measure d₀, d_i, h_i and note down the characteristics of the image.
2. Move the pencil to 2f. Record in Table 1.Measure d₀, d_i, h_iand note the characteristics of the image.
3. Move the pencil to between 2f and f. Record in Table 1. Measure d₀, d_i, h_i and characteristics of the image.
4. Place the pencil at f. Record your observations.
5. Move the pencil to a position that is halfway between f and the lens. If you cannot locate the image, check the box next to Virtual Image. Record your observations in Table 1.
6. Use thin lens equation to calculate the focal length.

Table 1: Convex lens

Position of Object	Beyond 2f (cm)	At 2f (cm)	Between 2f and f (cm)	At f (cm)	Between f and lens (cm)
do
di
hi
Real or virtual
Enlarged/ reduced/ same size
Inverted / Upright
Magnification
Magnification
Calculated focal length

Concave Lens

1. Choose the Diverging Lens (Concave).

1. Using the ruler, measure the distance from to the center of lens. Record this value as f below: Double this value and record as 2f.

f = _______________

2f = _______________

1. Measure the height of object (h_o) using the vertical ruler and record below:

h_o = __________________

1. Place your chosen object beyond 2f. Record d_o, d_i, and h_i in Table 2.
2. Place your chosen object between 2f and f. Record d_o, d_i, and h_i in Table 2.
3. Place your chosen object at f. Record d_o, d_i, and h_i in Table 2.
4. Place your chosen object between f and concave lens. Record d_o, d_i, and h_i in Table 2.

Table 2: Concave Lens

Position of Object	Beyond 2f (cm)	At 2f (cm)	Between 2f and f (cm)	At f (cm)	Between f and lens (cm)
do
di
hi
Real or virtual
Enlarged/ reduced/ same size
Inverted / Upright
Magnification
Magnification
Calculated focal length

Question-1: Describe the conditions for forming a virtual image with convex lens?

Question-2: How does the image of a concave lens always appear? Where is it located with respect to the lens and the object?

Question-3: When the object is placed at focal length, where does the image form when using (a) convex lens and (b) concave lens?

Concave Mirror

1. Choose the Concave Mirror.

1. Using the ruler, measure the distance from to the center of lens. Record this value as f below: Double this value and record as 2f.

f = _______________

2f = _______________

1. Measure the height of object (h_o) using the vertical ruler and record below:

h_o = __________________

1. Place your chosen object at different positions mentioned in the Table 3. Record d_o, d_i, h_i, and characteristics of the image formed in Table 3.

Table 3: Concave Mirror

Position of Object	Beyond 2f (cm)	At 2f (cm)	Between 2f and f (cm)	At f (cm)	Between f and mirror (cm)
do
di
hi
Real or virtual
Enlarged/ reduced/ same size
Inverted / Upright
Magnification
Magnification
Calculated focal length

Convex Mirror

1. Choose the Convex Mirror.
2. Using the ruler, measure the distance from to the center of lens. Record this value as f below: Double this value and record as 2f.

f = _______________

2f = _______________

1. Measure the height of object (h_o) using the vertical ruler and record below:

h_o = __________________

1. Place your chosen object at different positions mentioned in the Table 4. d_o, d_i, h_i, and characteristics of the image formed in Table 4.

Table 4: Convex Mirror

Position of Object	Beyond 2f (cm)	At 2f (cm)	Between 2f and f (cm)	At f (cm)	Between f and mirror (cm)
do
di
hi
Real or virtual
Enlarged/ reduced/ same size
Inverted / Upright
Magnification
Magnification
Calculated focal length

Question 5:Is concave mirror a converging or diverging mirror?

Question 6:Does concave mirror produce a virtual image?

PHYS 1402 Lab: Thin Lenses and Spherical Mirrors

Name: _______________________________

Objectives

• To demonstrate the formation of images from convex and concave lenses.
• To identify the type of image formed by convex and concave lenses.
• To identify the type of image formed by concave mirror.

Key Terms

1. Converging (or convex lens): lens in which light rays that enter it parallel converge into a single point on the opposite side.
2. Diverging (or concave lens): lens that causes light rays to bend away from its optical axis.
3. Focal Point F: for a converging lens or mirror, the point at which converging light rays cross; for a diverging lens or mirror, the point from which diverging light rays appear to originate.
4. Focal length f: distance along the optical axis from the focal point to the Lens (or Mirror) that focuses the light rays.
5. Object distance d₀: distance between the object and lens (or mirror).
6. Image distance d_i: distance between the image formed and lens (or mirror).
7. Magnification . If m > 1, then image is enlarged; if m

Convex lens

1. Open Geometric Optics
2. Take some time to play with the simulation to get familiar with how it works.
3. Maximize your screen.
4. In this lab, you will be moving the object to analyze how images are formed. When you are ready to get started, be sure that your settings are as follows:

1. Select Principal Rays
2. Check the box: Focal points (F)
3. Check the box: Virtual Image

1. Use the ruler in the PhET program to measure the distances and height.
2. Using the ruler, measure the distance from to the center of lens.
3. Record this value as f below: Double this value and record as 2f.

f = _______________

2f = _______________

1. Measure the height of object (h_o) using the vertical ruler and record.

Just measure the height of the pencil or penguin. Do not include the height of frame in your measurement.

h_o = ________

1. Place the pencil beyond 2f. Measure d₀, d_i, h_i and note down the characteristics of the image.
2. Move the pencil to 2f. Record in Table 1.Measure d₀, d_i, h_iand note the characteristics of the image.
3. Move the pencil to between 2f and f. Record in Table 1. Measure d₀, d_i, h_i and characteristics of the image.
4. Place the pencil at f. Record your observations.
5. Move the pencil to a position that is halfway between f and the lens. If you cannot locate the image, check the box next to Virtual Image. Record your observations in Table 1.
6. Use thin lens equation to calculate the focal length.

Table 1: Convex lens

Position of Object	Beyond 2f (cm)	At 2f (cm)	Between 2f and f (cm)	At f (cm)	Between f and lens (cm)
do
di
hi
Real or virtual
Enlarged/ reduced/ same size
Inverted / Upright
Magnification
Magnification
Calculated focal length

Concave Lens

1. Choose the Diverging Lens (Concave).

1. Using the ruler, measure the distance from to the center of lens. Record this value as f below: Double this value and record as 2f.

f = _______________

2f = _______________

1. Measure the height of object (h_o) using the vertical ruler and record below:

h_o = __________________

1. Place your chosen object beyond 2f. Record d_o, d_i, and h_i in Table 2.
2. Place your chosen object between 2f and f. Record d_o, d_i, and h_i in Table 2.
3. Place your chosen object at f. Record d_o, d_i, and h_i in Table 2.
4. Place your chosen object between f and concave lens. Record d_o, d_i, and h_i in Table 2.

Table 2: Concave Lens

Position of Object	Beyond 2f (cm)	At 2f (cm)	Between 2f and f (cm)	At f (cm)	Between f and lens (cm)
do
di
hi
Real or virtual
Enlarged/ reduced/ same size
Inverted / Upright
Magnification
Magnification
Calculated focal length

Question-1: Describe the conditions for forming a virtual image with convex lens?

Question-2: How does the image of a concave lens always appear? Where is it located with respect to the lens and the object?

Question-3: When the object is placed at focal length, where does the image form when using (a) convex lens and (b) concave lens?

Concave Mirror

1. Choose the Concave Mirror.

1. Using the ruler, measure the distance from to the center of lens. Record this value as f below: Double this value and record as 2f.

f = _______________

2f = _______________

1. Measure the height of object (h_o) using the vertical ruler and record below:

h_o = __________________

1. Place your chosen object at different positions mentioned in the Table 3. Record d_o, d_i, h_i, and characteristics of the image formed in Table 3.

Table 3: Concave Mirror

Position of Object	Beyond 2f (cm)	At 2f (cm)	Between 2f and f (cm)	At f (cm)	Between f and mirror (cm)
do
di
hi
Real or virtual
Enlarged/ reduced/ same size
Inverted / Upright
Magnification
Magnification
Calculated focal length

Convex Mirror

1. Choose the Convex Mirror.
2. Using the ruler, measure the distance from to the center of lens. Record this value as f below: Double this value and record as 2f.

f = _______________

2f = _______________

1. Measure the height of object (h_o) using the vertical ruler and record below:

h_o = __________________

1. Place your chosen object at different positions mentioned in the Table 4. d_o, d_i, h_i, and characteristics of the image formed in Table 4.

Table 4: Convex Mirror

Position of Object	Beyond 2f (cm)	At 2f (cm)	Between 2f and f (cm)	At f (cm)	Between f and mirror (cm)
do
di
hi
Real or virtual
Enlarged/ reduced/ same size
Inverted / Upright
Magnification
Magnification
Calculated focal length

Question 5:Is concave mirror a converging or diverging mirror?

Question 6:Does concave mirror produce a virtual image?