Students can Download Chapter 15 Light Questions and Answers, Notes Pdf, KSEEB Solutions for Class 7 Science, Karnataka State Board Solutions help you to revise complete Syllabus and score more marks in your examinations.
Karnataka State Syllabus Class 7 Science Chapter 15 Light
Class 7 Science Light NCERT Textbook Questions and Answers
Fill in the blanks:
- An image that cannot be obtained on a screen is called a Virtual Image.
- The image formed by a convex mirror is always virtual and smaller in size.
- An image formed by a plane mirror is always of the same size as that of the object.
- An image which can be obtained on a screen is called a real image.
- An image formed by a concave lens cannot be obtained on a screen.
Mark ‘T’ if the statement is true and ‘F’ if it is fake:
(a) We can obtain an enlarged and erect image by a convex mirror. (T/F)
(b) A concave lens always forms a virtual image. (T/F)
(c) We can obtain a real, enlarged, and inverted image by a concave mirror. (T/F)
(d) A real image cannot be obtained on a screen. (T/F)
(e) A concave mirror always forms a real image. (T/F)
Match the items given in Column I with one or more items of Column II.
|Column I||Column II|
|(a) A plane mirror||(i) Used as a magnifying glass.|
|(b) A convex mirror||(ii) Can form image of objects spread over a large area.|
|(c) A convex lens||(iii) Used by dentists to see enlarged image of teeth.|
|(d) A concave mirror||(iv) The image is always inverted and magnified.|
|(e) A concave lens||(v) The image is erect and of the same size as the object.|
|(vi) The image is erect and smaller in size than the object.|
State the characteristics of the image formed by a plane mirror.
Characteristics of the image formed by a plane mirror.
- Virtual and erect.
- Behind the mirror
- Size of image is equal to size of object.
- Laterally inverted image
(image of left side visible on right side)
- Distance of image behind the mirror is equal to distance of object in front of mirror.
Find out the letters of the English alphabet or any other language known to you in which the image formed in a plane mirror appears exactly like the letter itself. Discuss your findings.
A, H, I, M, O, T, U, V, W, and X are the letters. Which form the same image as the letter is. These letters are laterally symmetrical.
What is a virtual image? Give one situation where a virtual image is formed.
The image which cannot be obtained on a screen is called a virtual image. When some object is placed very close to the concave mirror then we do not get any image on the screen placed behind the mirror. Such an image is called a virtual image.
State two differences between a convex and a concave lens.
- A convex lens can make images which are enlarged or smaller or equal to the size of the object whereas a concave lens can always make a smaller image.
- A convex lens makes both real image and virtual images whereas a concave lens always makes a virtual image.
Give one use each of a concave and a convex mirror.
Concave mirrors: They are used by dentists to see enlarged images of the patient’s teeth so that it becomes easier to locate the defect in the tooth.
Convex mirrors: They are used as rearview mirrors in vehicles to see the traffic coming from behind.
Which type of mirror can form a real image?
A concave mirror can form a real image.
Which type of lens forms always a virtual image?
A concave lens forms always a virtual image.
Choose the correct option in questions 11 – 13
A virtual image larger than the object can be produced by a
(i) concave lens
(ii) concave mirror
(iii) convex mirror
(iv) plane mirror
(ii) concave mirror
David is observing his image in a plane mirror. The distance between the mirror and his image is 4 m. If he moves 1 m towards the mirror, then the distance between David and his image will be
(i) 3 m
(ii) 5 m
(iii) 6 m
(iv) 8 m
(iii) 6 m
Explanation: As David moves 1 m towards the mirror, the image also moves 1 m towards the mirror. Now the distance between David and the mirror is 3m and the distance between the mirror and the image is 3m. So, the total distance between David and his image will be 6m
The rearview mirror of a car is a plane mirror. A driver is reversing his car at a speed of 2 m/s. The driver sees in his rearview mirror the image of a truck parked behind his car. The speed at which the image of the truck appears to approach the driver will be
(i) 1 m/s
(ii) 2 m/s
(iii) 4 m/s
(iv) 8 m/s
(iii) 4 m/s
Explanation: As the car moves 2m/s backward, the mirror also moves 2m/s backward, so images come 4m/s forward. (i.e., 2m/s + 2ms)
Class 7 Science Light Additional Important Questions and Answers
What is light? What is its important Property?
Light is a form of energy. It always travels in a straight line. Whenever it falls on the smooth surface, it changes its direction is called a reflection of light.
Define the mirror.
A smooth shiny surface of the glass which reflects light is called a mirror.
How many types of mirrors are there? Name them, define them.
There are 3 types of mirrors.
- Plane mirror: The name itself indicates that this mirror has a plane surface. This type of mirror is used in our homes.
- Concave mirror: The inner surface of the spherical mirror is reflecting, then it is said to be a concave mirror.
- convex mirror: The outer surface of the spherical mirror is reflecting, then it is said to be a convex mirror.
How many colours in the Rainbow?
There are 7 colours in the Rainbow. They are VIBGYOR. It means Violet, Indigo, Blue, Green, Yellow, Orange, and Red.
What is meant by Newton’s disc? Explain with a neat diagram.
Newton’s colour disc has seven equal parts coloured with rainbow colours. Make a small hole at the centre of the disc Insert a stick. Ensure that the disc rotates freely. When the disc rotated fast, the colours get mixed together and appears to be whitish.
II. Fill in the blanks :
- After the rain when the sun is low in the sky the rainbow appears in the Sky.
- A Prism splits a beam of sunlight into seven colours.
- When we blow soap bubbles they appear colourful.
- Concave mirror is Converging in nature.
- Convex mirror is diverging in nature.
- Image obtained on Screen is a real image.