(LIGHT, SHADOWS AND REFLECTION) AND (ELECTRICITY AND CIRCUITS) PRACTICE WORKSHEET Class – 6

(LIGHT, SHADOWS AND REFLECTION) AND (ELECTRICITY AND CIRCUITS) 

PRACTICE WORKSHEET 

Class – 6

1.      Fill in the blanks:         (5 marks)

a.       We cannot see a _____________object in the dark.              (luminous/non-luminous)

b.      ______________ objects allow light to pass through them.  (Opaque/Transparent)

c.       Light travels in a _____________ line.                                  (straight/curved)

d.      Translucent objects block the light __________________.   (completely/partially)

                  e.     Image formed on pinhole camera is always __________.       (erect/inverted)

Ans. a. non-luminous
        b. Transparent 
        c. straight
        d. partially
        e. inverted

2.      Three identical shirts of red, blue and green colours are hanging on a rope in the sun. What would be the colour of their shadows and why?      (1 mark)

Ans. The colour of their shadows will be black only because shadows are always black in colour.

3.     Look at the figure:      (1 mark)












Will there be any difference in the shadow formed on the screen in A and B? Justify your answer.

Ans. No, there will not be any difference in the shadow formed on the screen in A and B because torches & screens are at same distances from object and light in both cases is blocked by the circular surfaces/ends of same radius.

4.   We see the moon shinning at night. Then, why do we call it non luminous body?      (1 mark)
Ans. We call it non luminous body because it does not have light of its own. It gets illuminated by sunlight and we see the reflection of sunlight from moon. 

5.   What happens to the size of shadow of an opaque object when object is brought close to the screen and away from the light source? (1 mark)
Ans. The size of shadow decreases.

6.   If a student stands 3m in front of a mirror, what is the distance between he and his image?  (1 mark)

 Ans. Plane mirror forms an image behind the mirror at equal distance as that of object from the mirror. So, the distance between he and his image = 3m + 3m = 6m.

7. What do you mean by reflection of light?     (1 mark)
Ans. The bouncing back of light which fall on surface of an object into same medium is called reflection of light.

8. What is the direction of electric current in an electric circuit?   (1 mark)
Ans. Electric current in an electric circuit flows from Positive terminal of a cell to negative terminal of the electric cell.

9.  What is an electric circuit?      (1 mark)
Ans. An electric circuit is a path along which electricity can flow. It provides a complete path for electricity to pass between the two terminals of an electric cell.

10. Never join the two terminals of the electric cell without connecting them through a switch and a device like a bulb. Give reasons.    (2 marks)
Ans. This is because if we join the two terminals of a cell directly by a wire only, then the chemicals present in the cell get used up very fast, the cell gets damaged quickly and hence stops working.

11.   Differentiate between shadows and images.     (2 marks)
Ans. 

Shadows

Images

Shadows are formed when light rays are blocked by an object.

Images are formed due to reflection or refraction.

Shadows are always black in colour.

Images are of same colour as the object.

Shadows are always erect.

Images can be erect (like in plane mirror)or inverted (like in pinhole camera)

Shadows give the outline of an object.

Images give details and outline of the object.

12.  When is a bulb said to be fused and why?     (2 marks)
Ans. When the filament (thin wire) of a bulb gets broken, the bulb is said to be fused. A break in filament of a bulb means a break in the path of electricity between the terminals of the cell. So, the circuit gets broken and electricity cannot pass through it even if it is connected properly to a cell.

13. Conductors and insulators are equally important for us. Give reasons.          (2 marks)
Ans. Conductors are the materials which allow electric current to pass through them. So, conductors are used to carry electricity. For example, electricity is carried in our homes by copper wires.
Insulators are the materials which do not allow electric current to pass through them. So, insulators are helpful in dealing with electricity without any harms/electric shock. For example, the plastic insulation over wires makes the electric wires safe to touch.

14. Given below is the conversation among various components/ phenomena found in an electric circuit. Read the conversation carefully and recognize these various speakers:      (6 marks)

Speaker A: Hello friends! Let us get together to make our beautiful and fragile friend ‘B’ glow.

Speaker B: Oh yes friends, I too want to light up this room. Will you please help me?

Speaker C: Ok! Let me help you all to connect with each other. Then our dear friend ‘D’ can easily move from one of you to another.

Speaker D: Certainly, but I need to be controlled by ‘A’. Friend ‘A’, please let me move through ‘C’ only when required. Will you please do that?

Speaker A: Oh sure! But where is our friend ‘E’? It is one of the most important and necessary part. None of us will be able to work without ‘E.

Speaker ‘E’: Sorry friends! I got late. Actually, I was lying idle for a very long inside a toy car. But, now I am ready to work.

All of them got together to form an ___________.

Name each component/ phenomenon below:

Speaker ‘A’ ________

Speaker ‘B’ _______

Speaker ‘C’ ________

Speaker ‘D’ _______

Speaker ‘E’ _______

Ans. All of them got together to form an electric circuit.

Each component/ phenomenon below is:

Speaker ‘A' = Switch

Speaker ‘B’ = Electric bulb

Speaker ‘C’ = Connecting wires

Speaker ‘D’ = Current

Speaker ‘E’ = Cell or Battery

15. Solve the crossword puzzle with the help of clues given below:       (8 marks)

Ans. Across

        1. Insulator

        2. Conductor

        3. Filament

        8. Cell
        

        Down

    4. Plastic

    5. Battery

    6. Copper

    7. Switch

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