Light Worksheet

Objective Type Questions

Match the following:

State whether the statement is true or false:
Regular reflection occurs when light waves bounce off a smooth surface at the same angle they hit.

State whether the statement is true or false:
The laws of reflection state that the angle of incidence (i) is always greater than the angle of reflection (r).
Label the diagram:
The below image shows the structure of the human eye. Complete the following
diagram with appropriate labels.
Match items in List A with the item in List B:
Unscramble the following words:
(a) BEILRAL
(b)KELOIDASCOPE
(c) LIPUP

Multiple Choice Questions
If you were to place a non-luminous object in a completely dark room with no light sources, would you be able to see it?
(a) Yes, because all objects are visible in the dark.
(b) No, because there is no light to reflect off the object.
(c) Yes, because the object will eventually start emitting light.
(d) No, because the object will absorb all the light in the room.
In a ray diagram showing the reflection of light from a mirror, the incident ray is represented by:
(a) A solid line with an arrow pointing towards the mirror.
(b) A dashed line with an arrow pointing towards the mirror.
(c) A solid line with an arrow pointing away from the mirror.
(d) A dashed line with an arrow pointing away from the mirror.
Two mirrors A and B are placed at right angles to each other. A ray of light incident on mirror A at an angle of 25° falls on mirror B after reflection. The angle of reflection for the ray reflected from mirror B would be:
(a) 25°
(b) 50°
(c) 65°
(d) 115°
Rohit is performing an experiment using a piece of paper marked with a dot and a cross with a black marker, as shown below. He notices that the round mark disappears when he moves the paper close to his face.

Which of the following conclusion is most likely correct?
(a) Rohit has a problem with his vision.
(b) The round mark is not visible because it falls on Rohit’s blind spot.
(c) The round mark is too small to be seen at close distances.
(d) The cross marker appears to be clearer because of its shape.
While playing outside, Ravi feels a sharp pain in his eye. What immediate action should he take to protect his eyes?
(a) Rub his eyes vigorously.
(b) Rinse his eyes with clean water.
(c) Ignore the pain and continue playing.
(d) Cover his eyes with his hands.
In a science experiment, Riya shines a flashlight on a crumpled aluminium foil and observes that the light scatters in different directions. This is an example of:
(a) Regular reflection
(b) Diffused refraction
(c) Dispersion of light
(d) Diffused reflection

Subjective Questions
Neha is experiencing eye strain while watching TV in a dark room. What measures can she take to protect her eyes?
Give an example of a rough surface and explain how reflection from this surface differs from reflection from a smooth surface.
Rohit is conducting an experiment with white light and different coloured objects. Can you explain to him what colour an object will appear to be in the following
cases:
(i) It reflects all colours.
(ii) It absorbs all colours.
(iii) It reflects green light and absorbs other colours.
(iv) It reflects red light and absorbs other colours.
When you stand in front of a large plane mirror, describe four characteristics of the image it forms.

Assertion-Reasoning Questions
Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
Assertion: Some persons may lose their eyesight because of a disease or an injury.
Reason: Visually impaired person develops their other senses more sharply.
Assertion: A kaleidoscope uses multiple mirrors to create beautiful patterns.
Reason: Using repeated reflections, kaleidoscopes create intricate patterns.
Assertion: The irregularities in the reflecting surface, such as that of cardboard, cause irregular reflection.
Reason: Diffused or irregular reflection occurs when all of the parallel rays reflected from a rough or irregular surface are parallel to each other.

Case-Based Questions
Ravi and Priya were playing together with a torch. Ravi is fascinated by the human eye and notices that her pupil dilates when he shines a torch in Priya's eye. He decides to experiment to figure out why this is happening.

Ravi instructs Priya to look straight ahead while he measures the size of her pupil. He then shines a torch into her eye and examines the pupil again. He turns off the torch and returns his attention to the student. When he shines the torch on the eye, he notices that the size of the pupil changes.
Note: Flashing a torch or flashlight is not recommended as it can cause permanent
damage to the eye. The question is only meant to be a concept application.
(a) Both A and R are true, and R is the correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.

Answer the following question based on the given information.
(a) What is the function of the pupil in the human eye?
(b) Why does the size of the pupil change when light is shone on the eye?
(c) In which case was Priya's pupil larger - when the torch was switched on or off? Justify your answer.
(d) How does the size of the pupil affect the amount of light entering the eye?
(e) What role does the iris play in controlling the size of the pupil and regulating the amount of light entering the eye?

Objective Type Questions

Match the following:

Solution:

State whether the statement is true or false:
Regular reflection occurs when light waves bounce off a smooth surface at the same angle they hit.
Correct answer: True
Regular reflection occurs when light waves bounce off a smooth surface at the same angle they hit.

State whether the statement is true or false:
The laws of reflection state that the angle of incidence (i) is always greater than the angle of reflection (r).
Correct answer: False
According to the law of reflection,
The angle of incidence, ∠i = angle of reflection, ∠r
Label the diagram:
The below image shows the structure of the human eye. Complete the following
diagram with appropriate labels.

Solution:
Match items in List A with the item in List B:

Solution:
Unscramble the following words:
(a) BEILRAL
(b)KELOIDASCOPE
(c) LIPUP
Solution:
(a) BRAILLE
(b) KALEIDOSCOPE
(c) PUPIL

Multiple Choice Questions
If you were to place a non-luminous object in a completely dark room with no light sources, would you be able to see it?
(a) Yes, because all objects are visible in the dark.
(b) No, because there is no light to reflect off the object.
(c) Yes, because the object will eventually start emitting light.
(d) No, because the object will absorb all the light in the room.
Correct option: (b) No, because there is no light to reflect off the object.
Solution:
Without any light sources, no light would be available to illuminate the object and reflect off it, making it invisible to the human eye.
In a ray diagram showing the reflection of light from a mirror, the incident ray is represented by:
(a) A solid line with an arrow pointing towards the mirror.
(b) A dashed line with an arrow pointing towards the mirror.
(c) A solid line with an arrow pointing away from the mirror.
(d) A dashed line with an arrow pointing away from the mirror.
Correct option: (a) A solid line with an arrow pointing towards the mirror.
Solution:
In a ray diagram showing the reflection of light from a mirror, the incident ray is typically represented by a solid line with an arrow pointing towards the mirror.

This indicates the direction in which the light approaches the mirror before reflection occurs.
Two mirrors A and B are placed at right angles to each other. A ray of light incident on mirror A at an angle of 25° falls on mirror B after reflection. The angle of reflection for the ray reflected from mirror B would be:
(a) 25°
(b) 50°
(c) 65°
(d) 115°
Correct option: (c) 65°
Solution:
According to the laws of reflection:
angle of incidence = angle of reflection
Now, given that the angle of incidence on mirror A is 25°
25° = 90° - x
i.e., x = 90° - 25°
∴ x = 65°
Now with the help of the ray diagram, we can conclude that the angle of the reflected ray from mirror B is 65°.
Rohit is performing an experiment using a piece of paper marked with a dot and a cross with a black marker, as shown below. He notices that the round mark disappears when he moves the paper close to his face.

Which of the following conclusion is most likely correct?
(a) Rohit has a problem with his vision.
(b) The round mark is not visible because it falls on Rohit’s blind spot.
(c) The round mark is too small to be seen at close distances.
(d) The cross marker appears to be clearer because of its shape.
Correct option: (b) The round mark is not visible because it falls on Rohit’s blind spot.
Solution:
The round mark disappearing when the paper is moved close to Rohit's face suggests that it falls on his blind spot, as described in the blind spot experiment, where a point on the retina cannot send messages to the brain when light falls on it.
While playing outside, Ravi feels a sharp pain in his eye. What immediate action should he take to protect his eyes?
(a) Rub his eyes vigorously.
(b) Rinse his eyes with clean water.
(c) Ignore the pain and continue playing.
(d) Cover his eyes with his hands.
Correct option: (b) Rinse his eyes with clean water.
Solution:
Ravi should rinse his eyes with clean water to flush out any foreign particles or irritants causing the pain and soothe his eyes.
In a science experiment, Riya shines a flashlight on a crumpled aluminium foil and observes that the light scatters in different directions. This is an example of:
(a) Regular reflection
(b) Diffused refraction
(c) Dispersion of light
(d) Diffused reflection
Correct option: (b) Diffused reflection
Solution:
When Riya shines a flashlight on the crumpled aluminium foil and observes that the light scatters in different directions, it indicates diffused reflection, in diffused reflection, the light rays are reflected in various directions due to the irregularities on the surface, causing the scattered reflection of light.

Subjective Questions
Neha is experiencing eye strain while watching TV in a dark room. What measures can she take to protect her eyes?
Solution:
To protect her eyes from strain while watching TV in a dark room, Neha should adjust the lighting, take regular breaks, and maintain a proper distance.
Give an example of a rough surface and explain how reflection from this surface differs from reflection from a smooth surface.
Solution:
A rough surface, such as unpolished wood, exhibits diffused reflection where light scatters in different directions due to surface irregularities. This results in a lack of clear, well-defined images.

In contrast, like a polished mirror, a smooth surface shows regular reflection where light follows the laws of reflection, forming clear and well-defined images.
Rohit is conducting an experiment with white light and different coloured objects. Can you explain to him what colour an object will appear to be in the following
cases:
(i) It reflects all colours.
(ii) It absorbs all colours.
(iii) It reflects green light and absorbs other colours.
(iv) It reflects red light and absorbs other colours.
Solution:
An object appears.
(i)White: When it reflects all colours.
(ii)Black: When it absorbs all colours.
(iii)Green: When it reflects green light and absorbs other colours.
(iv)Red: When it reflects red light and absorbs other colours.
When you stand in front of a large plane mirror, describe four characteristics of the image it forms.
Solution:
Four characteristics of an image formed by a plane mirror are:
(i)The image is always erect and virtual.
(ii)Image size is the same as object size.
(iii)The image is laterally inverted.
(iv)The image distance is the same as the object distance.

Assertion-Reasoning Questions
Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
Assertion: Some persons may lose their eyesight because of a disease or an injury.
Reason: Visually impaired person develops their other senses more sharply.
Correct option: (b) Both A and R are true, but R is not the correct explanation of the assertion.
For the given case, both A and R are true; however, R is not the correct explanation for A because the development of other senses in people who are blind is not directly related to the cause of their blindness.
Assertion: A kaleidoscope uses multiple mirrors to create beautiful patterns.
Reason: Using repeated reflections, kaleidoscopes create intricate patterns.
Correct option: (a) Both A and R are true, and R is the correct explanation of the assertion.
A kaleidoscope creates stunning patterns with several mirrors using repeated reflections to form elaborate patterns.
Assertion: The irregularities in the reflecting surface, such as that of cardboard, cause irregular reflection.
Reason: Diffused or irregular reflection occurs when all of the parallel rays reflected from a rough or irregular surface are parallel to each other.
Correct option: (c) A is true, but R is false.
Inconsistent reflection is caused by irregularities in the reflecting surface, such as that of cardboard. When all parallel rays reflected from a rough or irregular surface are not parallel, this is called diffused or irregular reflection.

Case-Based Questions
Ravi and Priya were playing together with a torch. Ravi is fascinated by the human eye and notices that her pupil dilates when he shines a torch in Priya's eye. He decides to experiment to figure out why this is happening.

Ravi instructs Priya to look straight ahead while he measures the size of her pupil. He then shines a torch into her eye and examines the pupil again. He turns off the torch and returns his attention to the student. When he shines the torch on the eye, he notices that the size of the pupil changes.
Note: Flashing a torch or flashlight is not recommended as it can cause permanent
damage to the eye. The question is only meant to be a concept application.
(a) Both A and R are true, and R is the correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.

Answer the following question based on the given information.
(a) What is the function of the pupil in the human eye?
(b) Why does the size of the pupil change when light is shone on the eye?
(c) In which case was Priya's pupil larger - when the torch was switched on or off? Justify your answer.
(d) How does the size of the pupil affect the amount of light entering the eye?
(e) What role does the iris play in controlling the size of the pupil and regulating the amount of light entering the eye?
Solution:
(a) The pupil is the black opening in the middle of the coloured part of our eye (iris). Its function is to control the amount of light entering the eye.
(b) The size of the pupil changes in response to light because it is controlled by muscles in the iris that contract or relax depending on how much light is available.
• When exposed to bright light, the muscles contract, shrinking the pupil and allowing less light into the eye.
• When the light is dim, the muscles relax, causing the pupil to dilate and allowing more light into the eye.
(c) Priya's pupil grew larger when the torch was turned off because there was less light available, so her iris muscles relaxed, allowing more light into her eye.
(d) The size of the pupil affects the amount of light entering your eye by controlling how much light can pass through it. For example, when it is larger, more light can enter your eye, and when it is smaller, less light can enter your eye.
(e) The iris plays a role in controlling the size of the pupil by using its muscles to contract or relax depending on how much light is available. This regulates the amount of light entering your eye by changing the size of your pupil.