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Solve Exercise 1 on page 25 Physics Grade 7 Textbook
Problem statement:
Choose the correct answer to the question: 'When do we see an object?'
A. When the object is illuminated;
B. When the object emits light;
C. When there is light from the object entering our eyes;
D. When there is light from our eyes illuminating the object.
Solution:
Answer C.
We see an object when there is light from the object entering our eyes.
Solution to Exercise 2 on page 25 Physics Grade 7 Textbook
Problem statement:
Select the correct statement among the following statements about the image of an object formed by a plane mirror:
A. The virtual image is smaller than the object and closer to the mirror than the object.
B. The virtual image is equal to the object and is at a distance from the mirror equal to the distance from the object to the mirror.
C. The real image is formed on a screen and is the same size as the object;
D. The image cannot be formed on a screen and is smaller than the object.
Solution:
Answer B.
The image of an object formed by a plane mirror: the virtual image is equal to the object and is at a distance from the mirror equal to the distance from the object to the mirror.
Solve Exercise 3 on page 25 of Physics Grade 7 Textbook
Problem statement:
Law of straight propagation of light:
In a .... and .... environment, light travels in a .....
Solution:
In a transparent and homogeneous environment, light travels in a straight line.
Solution to Exercise 4 on page 25 of Physics Grade 7 Textbook
Problem statement:
When a ray of light encounters a plane mirror, it reflects according to the law of reflection:
a) The reflected ray lies in the same plane as the ..... and the .....
b) The angle of reflection is equal to the angle of incidence.
Solution:
a) The reflected ray lies in the same plane as the incident ray and the normal to the mirror at the point of incidence.
b) The angle of reflection is equal to the angle of incidence.
Solution to Exercise 5 on page 25 of Physics Grade 7 Textbook
Problem Statement:
What is the image formed by a flat mirror? How does the size of the image and the distance from the image to the mirror compare to the size of the object and the distance from the object to the mirror?
Solution:
The image of an object formed by a flat mirror is a virtual image.
The size of the image and the distance from the image to the mirror are equal to the size of the object and the distance from the object to the mirror.
Solution to Exercise 6 on page 25 of Physics Grade 7 Textbook
Problem Statement:
Question:
Answer:
The image of an object formed by a convex mirror shares similar characteristics with the image of an object formed by a flat mirror in that both are virtual images; they differ in that the image formed by a convex mirror is smaller than the image formed by a flat mirror.
Solution to Exercise 7 on page 25 of Physics Grade 7 Textbook
Solution to Exercise 8 on page 25 of Physics Grade 7 Textbook
Question:
Answer:
- When the object is placed close to the concave mirror.
- The virtual image formed by a concave mirror cannot be captured on a screen and is larger than the object.
Answer:
Solution to Exercise 8 on page 25 of Physics Grade 7 Textbook
Question:
Solution:
- The virtual image created by a concave mirror cannot be caught on a screen and is larger than the object.
- The virtual image produced by a convex mirror cannot be caught on a screen and is smaller than the object.
- The virtual image formed by a flat mirror cannot be caught on a screen and is equal to the object.
Comparing a flat mirror and a convex mirror of the same size. Compare their visible areas when the eye is placed at the same position relative to the mirrors.
Question:
There are two light sources S1, S2 placed in front of a flat mirror as shown in figure 9.1
Solution:
The visible area of the convex mirror is wider than the visible area of the flat mirror of the same size.
Solution to Exercise C1 on page 26 of Physics Grade 7 textbook
Question:
There are two light sources S1, S2 placed in front of a flat mirror as shown in figure 9.1
a) Draw the images of each point formed by the mirror.
b) Draw two largest incident light rays originating from S1, S2 and the corresponding reflected rays on the mirror.
c) In which area will the eyes simultaneously see the images of both light sources in the mirror? Cross-hatch that area.
Solution:
Problem Statement:
A person stands in front of three mirrors (flat mirror, convex mirror, concave mirror), equidistant from each other. When observing their virtual images in the three mirrors, what similarities and differences will they notice?
Solution:
- Similarity: The observed images in the three mirrors are all virtual images.
- Points of Distinction:
• Virtual images formed by the flat mirror are the same size as the person standing in front of the mirror.
• Images formed by the convex mirror are smaller than the person standing in front of the mirror.
• Images formed by the concave mirror are larger than the person standing in front of the mirror.
Solve exercise C3 on page 26 of Physics 7 textbook
Problem Statement:
There are four students standing at four positions around a cupboard as shown in Figure 9.2. Identify the pairs of students who can see each other. Mark those pairs on the following table.
Solution:
In the Physics 7 program, Chapter I on Optics, students will engage in a hands-on experiment: Observing and sketching an image created by a flat mirror. Solve exercises on page 18 of Physics 7 to master this lesson effectively.
Sound Source is the next topic in Chapter I of Optics in Physics 7 for 11th grade. Refer to the hints for solving exercises on pages 28 and 29 of Physics 7 to grasp the knowledge well and excel in Physics 7.
