RBSE Class 7 Science Important Questions Chapter 15 Light

Rajasthan Board  RBSE Class 7 Science Important Questions Chapter 15 Light Important Questions and Answers.

RBSE Class 7 Science Chapter 15 Important Questions Light

Multiple Choice Questions

Question 1. 
The distance between the mirror and Manya’s image is 5 m. If Manya moves 1 m towards the mirror, the distance between her and the image is:
(a) 2 m 
(b) 3 m
(c) 4 m 
(d) 8 m
Answer:
(d) 8 m

Question 2. 
The angle between the reflected ray and the normal is known as:
(a) angle of contact 
(b) angle of normal
(c) angle of reflection
(d) angle of dispersion
Answer:
(c) angle of reflection

 
Question 3. 
The rays of light that bounce back are known as:
(a) normal rays
(b) perpendicular rays 
(c) reflected rays 
(d) incident rays
Answer:
(c) reflected rays

Question 4. 
Curved mirrors are never:
(a) convex 
(b) plane
(c) concave 
(d) none of these
Answer:
(b) plane

Question 5. 
A magnifying glass is made of:
(a) convex mirror 
(b) concave mirror 
(c) convex lens 
(d) concave lens
Answer:
(c) convex lens

Question 6. 
A lens of concave nature can form:
(a) only virtual images
(b) only inverted images
(c) only real images
(d) only large images 
Answer:
(a) only virtual images

Fill in the blanks

Question 1. 
The human eye forms an inverted image on .................. after passing through the lens.
Answer:
retina

Question 2. 
.................. mirror is used as a rear view mirror.
Answer:
Convex

Question 3. 
A convex mirror never forms .................. images.
Answer:
real

Question 4.   
................. has seven colors of the rainbow painted on it.
Answer:
Newton’s disc

Question 5.  
.................. are widely used in spectacles to correct defects of vision.
Answer:
Lens

State Whether True or False

Question 1. 
A plane mirror always forms a real image.
Answer:
False

Question 2. 
A rainbow is made up of VIBGYOR.
Answer:
True

Question 3. 
A plane mirror always forms an inverted image.
Answer:
False

Question 4. 
A concave lens is used in torches.
Answer:
False

Question 5. 
Light travels in a circular path.
Answer:
False

Match the following

Column I	Column II
1. Real	(a) cannot be obtained on screen
2. Virtual	(b) upright
3. Inverted on a screen	(c) can be obtained
4. Erect	(d) enlarged image
5. Magnified	(e) upside - down image
6. White light	(f) water surface
7. Plane mirror	(g) convex lens
8. Diverging lens	(h) seven colors
9. Converging lens	(i) laterally inverted
10. Reflection of light	(j) concave lens

Answer:

Column I	Column II
1. Real	(c) can be obtained
2. Virtual	(a) cannot be obtained on the screen
3. Inverted on a screen	(e) upside - down image
4. Erect	(b) upright
5. Magnified	(d) enlarged image
6. White light	(h) seven colors
7. Plane mirror	(i) laterally inverted
8. Diverging lens	(j) concave lens
9. Converging lens	(g) convex lens
10. Reflection of light	(f) water surface

Very Short Answer Type Questions

Question 1. 
Light travels in a straight line. What is this property called?
Answer: 
This property of light to travel in a straight line is called rectilinear propagation of light.

Question 2. 
Define ‘Reflection’.
Answer: 
Reflection is the bouncing back of a ray of light after striking a reflecting surface.

Question 3. 
What do you mean by mirror? 
Answer: 
A mirror is a smooth, polished surface that can reflect light rays forming an image.

Question 4. 
What do you understand by ‘lateral inversion’?
Answer: 
When the left side appears right and the right side appears left. It is called lateral inversion.

Question 5. 
Raise your left hand. Which hand does your image raise in a plane mirror?
Answer: 
The image will raise the right hand, It is because, in the plane mirror, the ‘right’ appears ‘left’ and ‘left’ appears ‘right’.

Question 6. 
Name the spherical mirrors.
Answer: 
Concave mirror and convex mirror.

Question 7. 
A shopkeeper wanted to fix a mirror that will give a maximum view of his shop. What type of mirror should he use? Give reason.
Answer: 
He should use a convex mirror as it can form images of objects spread over a large area.

Question 8. 
What is the dispersion of light? 
Answer: 
The splitting of white light into seven colors is called dispersion of light. 

Question 9. 
Can we say that sunlight is a mixture of colors? 
Answer: 
Yes, sunlight is a mixture of various colors

Short Answer Type Questions

Question 1. 
What happens when the light falls on the mirror?
Answer: 
The mirror changes the direction of light that falls on it when light falls on the mirror it reflects back in a different direction. 

Question 2. 
What is a plane mirror?
Answer: 
A plane mirror is a sheet of glass with a silver shiny coating on one of its surfaces. The surface is responsible for the reflection of light.

Question 3. 
What is the difference between object and image?
Answer: 
If we look into the plane mirror, we can see ourselves in the mirror. This is our own image. In this case, our body is an object.

Question 4. 
What type of mirror is used as a side mirror in a scooter? Why is this type of mirror chosen?
Answer: 
A convex mirror is used as a side mirror in scooters. This type of mirror is chosen as it forms a smaller and virtual image. So, it can be used to see a much larger area than the area visible by a plane mirror.

Question 5. 
The side mirror of the scooter gets broken. The mechanic replaced it with a plane mirror. Mention any inconvenience that the driver of the scooter will face while using it.
Answer: 
A convex mirror is used as a rearview mirror in vehicles. If it is replaced with a plane mirror, the driver of the scooter will not be able to see the traffic spread over a large area behind him.

Question 6. 
What type of mirror is used by the dentist and other doctors? Why?
Answer: 
A concave mirror is used by doctors for examining eyes, ears, nose, and throat as it gives an enlarged view of the targeted object.

Question 7. 
Show the nature of convex and concave lenses diagrammatically.
Answer: 
A convex lens is converging in nature. It converges the light falling on it. 

The concave lens is diverging in nature. It diverges the light falling on it.

Question 8. 
What is a rainbow?
Answer: 
A rainbow is seen as a large curved write in reverse order area in the sky with many colors. It has seven colors: Violet, Indigo, Blue, Green, Yellow, Orange, and Red i.e. VIBGYOR.

Long Answer Type Questions

Question 1. 
Write the difference between regular reflection and irregular reflection.
Answer:
The difference between regular reflection and irregular reflection that takes place through a regular and smooth surface is known as regular reflection.

A reflection that takes place through a rough and dull surface is known as an irregular surface.

Question 2. 
Write the differences between real and virtual images.
Answer:
Differences between Real and Virtual image

Real image	Virtual image
The image which can be obtained on the screen is called a real image.	The image formed in the mirror is called
It is always inverted.	It is always erect.
A real image is formed by only a concave mirror.	A virtual image can be formed by concave, convex, and plane mirrors.

Question 3. List any three uses of a concave mirror.
Answer: 
Three uses of the concave mirror are:

1. Doctors use concave mirrors for examining the eyes, ears, nose, and throat.
2. Concave mirrors are also used by dentists to see an enlarged image of the teeth.
3. The reflectors of torches, headlights of cars, and scooters are concave in shape.

Question 4. 
List the use of concave lenses and convex lenses.
Answer: 
Convex lens:

1. It is used in magnifying glasses.
2. It is also used in a microscope, telescopes, etc.
3. It is also used in spectacles to correct for sightedness.

Question 5. 
Give an activity to show that reflection of light from a mirror.
Answer:

1. Take a torch and cover its glass with chart paper which has three slits as shown in the figure.
   
    
2. Spread a sheet of chart paper on a smooth wooden board and fix a plane mirror strip vertically on the chart paper.
3. Now direct the beam of light on the mirror from the torch with slits.
4. Place the torch in such a way that its light is seen along with the chart paper on the board.
5. Now adjust its position so that the light from the torch strikes the plane mirror at an angle
6. It is observed that the mirror reflects back the light striking it.
7. Now move the torch slightly to either side. It is noticed that the direction of the reflected light changes with respect to the incident light, and the angle of incidence always remains equal to the angle of reflection.

Question 6. 
Give an activity to show that seven colors can be mixed to get white light?
Answer:

(a) A disc Fig. (b) It appears with seven colors white on rotating

1. Take a circular cardboard disc of about 10 cm in diameter.
2. Divide this disc into seven segments.
3. Paint the seven rainbow colors on these segments.
4. Make a small hole at the center of the disc.
5. Fix the disc loosely on the tip of the refill of a ball pen. Ensure that the disc rotates freely.
6. Rotate the disc in sunlight.
7. When the disc gets rotated fast, the colors get mixed together and the disc appears to be whitish.
8. This disc is known as Newton’s disc.