Q1: Situation: A child noticed that the shadow becomes smaller when she stands close to a wall with a flashlight and moves the flashlight closer to the wall. However, the shadow becomes bigger when she moves the flashlight away from the wall. Why does this happen?
(a) The flashlight is too bright, causing the shadow to change size.
(b) The wall has magical properties that alter the shadow's size.
(c) The distance between the flashlight and the wall affects the size of the shadow.
(d) The flashlight produces different colours of light that influence the shadow size.
Ans: (c)
When the child moves the flashlight closer to the wall, the distance between the light source (flashlight) and the object (wall) decreases. As a result, the light rays from the flashlight become more concentrated, leading to a smaller and sharper shadow. Conversely, the distance increases when she moves the flashlight away from the wall, causing the light rays to spread out and create a larger and less defined shadow.
Q2: Situation: In the early morning and late afternoon, you might notice your shadow is much longer than during midday. Why does this happen?
(a) The Earth rotates faster during midday, causing shorter shadows.
(b) The Sun's position in the sky changes throughout the day, affecting shadow length.
(c) Shadows are naturally longer during the colder parts of the day.
(d) The atmosphere absorbs sunlight, causing shadows to stretch.
Ans: (b)
The length of a shadow is influenced by the position of the Sun in the sky. During early morning and late afternoon, the Sun is closer to the horizon, and its rays have to travel through a thicker layer of the Earth's atmosphere. This leads to longer shadows being cast. In contrast, during midday, the Sun is directly overhead, and its rays travel through a shorter path in the atmosphere, resulting in shorter shadows.
Q3: Situation: A group of students observed their shadows at different times of the day. They noticed that when they stood side by side, their shadows merged into one big shadow for some hours. What could be the possible reason for this phenomenon?
(a) The students' bodies overlap, creating a single large shadow.
(b) The Sun's rays are stronger during those hours, causing the shadows to merge.
(c) Shadows of nearby objects tend to merge during certain times of the day.
(d) The students' heights and positions affect the formation of the merged shadow.
Ans: (d)
When the students' shadows merge into one big shadow, it happens because their bodies are positioned in such a way that their shadows overlap and combine. The relative positions and heights of the students play a crucial role in determining how their shadows interact. If the students stand very close to each other or in a specific alignment, their shadows will merge to form a larger combined shadow.
Q4: Situation: During a science experiment, a student used a candle flame to cast a shadow on a white screen placed at different distances. Surprisingly, as the screen was moved closer to the candle flame, the shadow became blurry and less defined. Why did this happen?
(a) The candle flame produces multiple colours of light, causing blurriness.
(b) The white screen reflected too much light, making the shadow blurry.
(c) The candle flame has an irregular shape, leading to an unclear shadow.
(d) The light from the candle spreads out as it travels, causing the shadow to lose sharpness.
Ans: (d)
When light travels from the candle flame to the white screen, it spreads out in all directions. As the screen gets closer to the candle, the light rays become more divergent, leading to a larger and less defined shadow. This phenomenon is called "diffraction," where light waves bend and scatter around obstacles, resulting in a less focused shadow.
Q5: Situation: Two children are playing with their toy cars on a sunny day. Child A has a car with a shiny, reflective surface, while Child B's car has a dull, non-reflective surface. They both notice that the shiny car casts a fainter shadow compared to the dull car. Why does this happen?
(a) Shiny objects absorb more light, reducing the shadow's intensity.
(b) The reflective surface of the shiny car causes the shadow to appear faint.
(c) The shiny car reflects some light away, resulting in a less prominent shadow.
(d) The dull car's shadow is more pronounced due to the lack of reflection.
Ans: (c)
Shiny surfaces act as mirrors and reflect a significant portion of the incident light away from the object. When the shiny toy car is exposed to light, some of the light is redirected away from the surface, leading to a weaker shadow. On the other hand, the dull car's surface does not reflect much light, causing the shadow to be more pronounced since most of the incident light is absorbed by the object.
Q6: Situation: A student noticed that as they moved a transparent glass block towards the beam of light coming from a flashlight, the beam of light shifted its direction. What is this phenomenon called, and why does it occur?
(a) Light refraction - The light bends as it passes through the glass block due to the change in its speed.
(b) Light reflection - The glass block reflects the light beam, changing its direction.
(c) Light dispersion - The glass block breaks the light beam into different colours, causing a shift in direction.
(d) Light absorption - The glass block absorbs some of the light, altering the beam's path.
Ans: (a)
The phenomenon described in the situation is light refraction. When light passes through a transparent medium like glass, its speed changes and it bends or refracts. The angle of refraction depends on the refractive properties of the medium and the angle of incidence. This bending of light is what causes the beam of light to shift its direction when moving towards or through the glass block.
Q7: Situation: A group of students went on a field trip to a hilly area during sunrise. They noticed that while the trees and rocks cast clear shadows, the fog in the air did not cast any shadows. Why does fog not produce shadows?
(a) Fog absorbs all the light, leaving no shadows.
(b) Fog scatters the light in multiple directions, preventing the formation of shadows.
(c) Shadows are formed only when the Sun is at its peak position, not during sunrise.
(d) The presence of water droplets in the fog distorts the shadows.
Ans: (b)
Fog consists of tiny water droplets suspended in the air. When light passes through the fog, these droplets scatter the light in multiple directions, making it difficult for shadows to form. Unlike clear air, which allows light to travel in straight lines and create distinct shadows, the scattering effect of fog disperses the light and hinders the formation of well-defined shadows.
Q8: Situation: A student observed that when he stands near a tall building on a sunny day, his shadow appears to move slowly throughout the day. What causes this slow movement of the shadow?
(a) The tall building absorbs the sunlight, causing the shadow to move slowly.
(b) Shadows move slowly when there is a lack of wind in the area.
(c) The Earth's rotation causes the apparent movement of the Sun, which affects the shadow's position.
(d) The student's body temperature affects the speed of the shadow's movement.
Ans: (c)
The apparent movement of the Sun across the sky is caused by the rotation of the Earth. As the Earth spins on its axis, the position of the Sun in the sky appears to change, which, in turn, affects the position of the shadow. Throughout the day, the Sun's position gradually shifts, causing the shadow of the student near the tall building to move slowly in response to the changing angle of sunlight.
Q9: Situation: A child noticed that when he holds a small object close to a flashlight, the shadow of the object appears larger and more spread out on a wall. However, when he holds the same object far away from the flashlight, the shadow becomes smaller and more defined. Explain why this happens.
(a) The size of the object changes when it is moved closer or farther away from the flashlight.
(b) The flashlight produces different types of light that affect the shadow size.
(c) The distance between the object and the wall influences the size and sharpness of the shadow.
(d) The child's hand position while holding the object affects the shadow's appearance.
Ans: (c)
The size and sharpness of a shadow depend on the distance between the light source (flashlight) and the object (small object) and the distance between the object and the wall where the shadow is cast. When the object is held close to the flashlight, it is also closer to the wall. The light rays diverge more, creating a larger and less defined shadow on the wall. Conversely, when the object is held far away from the flashlight, it is also farther from the wall, causing the light rays to converge, resulting in a smaller and more defined shadow.
Q10: Situation: During a sunset, a child observed that the shadows of objects cast on the ground become longer and longer until they eventually disappear. Explain why this happens.
(a) Shadows disappear during a sunset due to the absence of sunlight.
(b) The Earth moves closer to the Sun during a sunset, causing shadows to vanish.
(c) The angle of sunlight becomes more acute during a sunset, elongating the shadows.
(d) Shadows are more prominent during the day, but they fade away during sunset.
Ans: (c)
During a sunset, the Sun is close to the horizon, and its rays have to travel through a thicker layer of the Earth's atmosphere before reaching the ground. As a result, the angle of sunlight becomes more acute or slanted. This slanted angle of sunlight elongates the shadows of objects cast on the ground, making them longer and longer until they eventually merge with the surrounding darkness and disappear as the Sun sets below the horizon.
