Light Shadows and Reflection Questions & Answers

Hi Everyone!! This article will share Light Shadows and Reflection Questions & Answers.

In my previous post, I have shared the Objective Type Questions & Answers of Light Shadows and Reflection so, make sure to check that post as well.

Light, Shadows and Reflection Questions & Answers

Question 1: Write any two artificial sources of light.

Answer: Bulb, torch, tube-light are artificial sources of light.

Question 2: How are objects visible to us?

Answer: Objects are visible to us only when light falling on objects is reflected. The reflected light reaches our eyes which make objects visible.

Question 3: Define the following.

(a) Light

Answer: Light is a form of energy that enables us to see the objects around us.

(b) Lateral inversion

Answer: In lateral inversion, the reflection of the image always reverses from left to right.

(c) Rectilinear propagation of light

Answer: The property of light travelling in a straight line in a homogeneous transparent medium is known as rectilinear propagation of light.

Question 4: When does a solar eclipse occur?

Answer: Solar eclipse occurs only on a new Moon day.

Question 5: What are sources of light? Name and explain the two groups into which all sources of light can be divided.

Answer:

  • An object which emits light is called a source of light.
  • All sources of light can be divided into two groups as Natural sources and artificial sources.
  • Those sources of light which exist in nature are called natural sources.
  • Those sources which have been made by man are called man-made or artificial sources of light.

Light, Shadows and Reflection Questions & Answers

Question 6: How are we able to see non-luminous objects? 

Answer: Non-luminous objects can only be seen if they reflect light from a luminous source. For example, Moon does not have its own light. It reflects the light coming from the Sun.

Question 7: List the conditions necessary for the formation of a shadow.

Answer:

  • A shadow is formed only when light is blocked by an opaque object. 
  • The colour of the shadow is always black irrespective of the colour of the object. 
  • The shape of the shadow may or may not resemble the actual shape of the object. 
  • A shadow can be formed only on a screen. 
  • The size of the shadow depends on the shape and size of the object and the position of the source of light.
  • A shadow does not show the details of an object.

Question 8: List the characteristics of an image formed in a plane mirror.

Answer:

  • The image is of the same size and same colour as that of the object. 
  • The image formed is laterally inverted.

Question 9: We are not able to see things behind a wall. What does this fact tell us about light? 

Answer: Those materials which do not allow any light to pass through them are called opaque materials. They absorb all the light radiations falling on them so we are not able to see things behind a wall.

Question 10: Distinguish between:

(a) Shadow and Image

ShadowImage
i. It is formed when light is obstructed by an opaque object.i. It is formed when light is reflected from the surface of a mirror.
ii. It is always black in colour.ii. It can have multiple colours.
iii. It is not laterally inverted.iii. It is laterally inverted.

(b) Luminous and Non-luminous objects

Luminous objectsNon-luminous objects
i. It emits light by itself.i. It does not emit light by itself.
ii. Example – Sun, Star, incandescent bulb, etc..ii. Example – Moon, Earth, ball, plants, etc.

(c) Solar eclipse and Lunar eclipse

Solar eclipseLunar eclipse
i. The shadow of the Moon falls on the Earth.i. The shadow of the Earth falls on the Moon.
i. The Moon comes exactly between the Sun and the Earth.ii. The Earth comes between the Sun and the Moon.
ii. It occurs only on a new Moon day.iii. It occurs only on a full Moon Day.

Question 11: Differentiate between transparent, translucent and opaque objects. 

Answer:

1. Transparent materials
Those materials which allow all the light to pass through them are called transparent materials. For example – water, air, glass, etc.
2. Translucent Materials
Those materials which allow some of the light to pass through them are called translucent materials. For example – butter paper, oiled paper, molten wax, frosted glass, etc.
3. Opaque Materials
Those materials which do not allow any light to pass through them are called opaque materials. They absorb all the light radiations falling on them. For example – Book, wall, wood, cardboard sheet, etc.

Light Shadows and Reflection Questions & Answers

Question 12: A house does not have electricity and remains dark during the day. Propose and plan steps that can be taken to allow more sunlight to enter the house.

Answer:

  • In order to increase the sunlight in the room, mirrors can be placed on the wall which is directly opposite the windows.
  • In this condition, sunlight enters from the windows and bounces and spreads from the surface of the mirrors.

Question 13: Explain that light travels in a straight line with the help of an activity.

Answer:

  • Take three pieces of cardboard and make a small hole at the centre of all three cardboards. The holes should be at the same position on all three cardboards.
  • Arrange and erect the cardboards in such a way that all the holes are in a straight line.
  • Take a lighted candle and place it in front of one of the cardboards. The candle should be of the height such that it can be seen from the holes of the cardboards.
  • Now, observe the flame of the candle from the hole of the last cardboard
  • Now misalign the cardboards so that the holes are not in a straight line. Observe the flame of the candle.
  • The flame of the candle will be seen when the holes are in a straight line and will not be seen when the holes are misaligned. This activity thus proves that the light travels in a straight line.

Question 14: A football match is being played at night in a stadium with flood lights ON. You can see the shadow of a football kept at the ground but cannot see its shadow when it is kicked in the air. Explain.

Answer: We can see the shadow of football lying on the ground because the ground acts as a screen for it. However, when the football is kicked high, the ground, which is acting as a screen is away from the football, hence no shadow of the football will be formed on the ground.

Question 15: Magnification is an enlarged image of an object. Then why is the magnification of a plane mirror always one?

Answer:

  • The image formed by a plane mirror is always of the same size as the real object.
  • The distance of the image from the plane mirror is also equal to the distance of the object from the mirror.
  • Therefore, the magnification of a plane mirror is always one.

Light Shadows and Reflection Questions & Answers

Question 16: On which principle does a pinhole camera work? What is the nature and colour of the image formed by a pinhole camera?

Answer:

  • The pinhole camera works on the principle of rectilinear propagation of light.
  • The image formed by a pinhole camera can be inverted, diminished or magnified.
  • The colour of the image is the same as that of the object.

Question 17: You are given a transparent glass sheet. Suggest any two ways to make it translucent without breaking it.

Answer:

  • By applying oil, grease, and butter on it or pasting butter paper on it.
  • Rubbing the surface of the glass by any abrasive material.

Question 18: Can an object have more than one shadow?

Answer: Yes, an object can have more than one shadow. This is possible when there are more than one source of light and they are placed in different directions. For example: In cricket field, where four light sources are placed in four directions and each player forms four shadows.

Question 19: What happens to:

(a) Image when distance between camera and object is reduced

Answer: Image of object will become larger.

(b) Shadow when distance between object and source increases.

Answer: Size of shadow decreases.

Question 20: What happens when light falls on object?

Answer: When light falls on an object, one or more of the following three things take place –

  • The light passes through the object.
  • The light gets absorbed by the object.
  • The light gets reflected by the object.

Question 21: Why we cannot see shadow of flying aeroplane/bird?

Answer: We cannot see it because it is so far up in the sky that its shadow is either too faint for us to see or shadow does not even reach the ground and is too fast for us to see.

So, these were Light, Shadows and Reflection Questions & Answers.