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Suggest a situation where we obtain more than one shadow of an object at a time.

The multiple shadows at a time of an object can be obtained when the light falls on the same object from different sources at a time like torch,... View Article

Correct the following statements. (i) The colour of the shadow of an object depends on its colour of the object. (ii) Transparent objects allow light to pass through them partially.

i) No, the colour of the object does not affect the colour of the image, because the shadow formed in always dark or black in colour. Shadow is... View Article

Look at the given figure. Will there be any difference in the shadow formed on the screen in A and B?

The same shadow will be formed on screen A and B because formation of the image depends on the size and shape of the opaque object. As the same... View Article

Three torches A, B and C shown in the figure are switched on one by one. The light from which of the torches will not form a shadow of the ball on the screen.

Torch A and B are placed in front of the screen so they will form image. As torch C is placed parallel to the screen, it will not form a shadow... View Article

Observe the picture given in figure A sheet of some material is placed at position ‘P’, still the patch of light is obtained on the screen. What is the type of material of this sheet?

P is the sheet of some transparent material like thin plastic, ground glass etc. Because only the transparent materials allows light to pass... View Article

You have 3 opaque strips with very small holes of different shapes as shown in the figure. If you obtain an image of the sun on a wall through these holes, will the image formed by these holes be the same or different?

All three objects will form the same kind of image of the sun irrespective of their shapes as the holes in the strips work as a pinhole camera... View Article

Two students while sitting across a table looked down on to its top surface. They noticed that they could see their own and each other’s image. The table top is likely to be made of (a) Unpolished wood (b) Red stone (c) Glass sheet (d) Wood top covered with cloth

c) Glass sheet All the other objects are opaque and non-reflecting in nature. And a glass sheet is transparent. Therefore, only it will reflect... View Article

Which of the following can never form a circular shadow? (a) A ball (b) A flat disc (c) A shoe box (d) An ice cream cone

c) A shoebox For forming the circular shadow the object should have a circular shape. A shadow is formed when an opaque object comes in the... View Article

Paheli observed the shadow of a tree at 8:00 a.m., 12:00 noon and 3:00 p.m. Which of the following statements is closest to her observation about the shape and size of the shadow? (a) The shape of the shadow of the tree changes but the size remains the same. (b) The size of the shadow of the tree changes but the shape remains the same. (c) Both the size and shape of the shadow of the tree change. (d) Neither the shape nor the size of the shadow changes.

c) Both the size and shape of the shadow of the tree change With the change in the time the direction of sun also changes hence the... View Article

Which of the following is/are not always necessary to observe a shadow? (a) Sun (b) Screen (c) Source of light (d) Opaque object

a) Sun Shadow can be formed from other sources of light also, like, torch. A shadow is actually just a space or region, where there is no... View Article

Four students A, B, C and D looked through pipes of different shapes to see a candle flame as shown in the figure. Who will be able to see the candle flame clearly? (a) A (b) B (c) C (d) D

d) D. The tube is straight in fig D. Therefore, candle flame will be visible clearly to us. The light always travels in the straight line.... View Article

A student observes a tree given in figure through a pinhole camera. Which of the diagrams given in figures (a) to (d) depicts the image seen by her correctly?

The image formed by pinhole camera is inverted and left - right reversed. Option (a) : the image is not inverted. Hence, option (a) is... View Article

Observe the picture given in figure carefully. A patch of light is obtained at B, when the torch is lighted as shown. Which of the following is kept at position A to get this patch of light? (b) A glass sheet (c) A mirror (d) A sheet of white paper,

Answer is (c) Mirror A mirror is kept at position A to get a patch of light because only a mirror can change the direction of light that falls... View Article

Boojho was riding in his bicycle along a straight road. He classified the motion of various parts of the bicycle as (i) rectilinear motion (ii) circular motion and (iii) both rectilinear as well as circular motion. Can you list one part of the bicycle for each type of motion? Support your answer with reason.

Type of Motion Part of bicycle Reason Rectilinear Handles The handles do not move in circular or rotatory motion. Circular Pedals The... View Article

Three students measured the length of a corridor and reported their measurements. The values of their measurements were different. What could be the reason for difference in their measurements? (Mention any three)

Reasons for different measurement could be- (i) Defective instrument or are not standardised. (ii) Wrong method of measurement. (iii) Use of... View Article

How are the motions of a wheel of a moving bicycle and a mark on the blade of a moving electric fan different? Explain.

Wheels of a moving bicycle show rectilinear motion and circular motion. Because when the wheel is rotating, it also moves the bicycle forward... View Article

While travelling in a train, it appears that the trees near the track are moving whereas co-passengers appear to be stationary. Explain the reason.

The trees appear to be in moving opposite direction while travelling in a train because the position of trees is changing with respect to us.... View Article

Four children measure the length of a table which was about 2m. Each of them used different ways to measure it. (i) Sam measured it with a half metre long thread. (ii) With a 15cm scale from her geometry box. (iii) Reena measured it using her hand span. (iv) Salim measured it using a 5m long measuring tape. Which one of them would get the most accurate length? Give reason for your answer.

(iv) Salim measured it using a 5m long measuring tape. The most accurate measurement will be done by Salim as he used a standard instrument to... View Article

The photograph given in figure shows a section of a grille made up of straight and curved iron bars. How would you measure the length of the bars of this section, so that the payment could be made to the contractor?

It is quite visible in the figure, the grille is made up of two types of iron bars, straight and curved. The curved rods can be measured with... View Article

Write one example for each of the following type of motion. (i) Rectilinear (ii) Circular (iii) Periodic (iv) Circular and periodic

(i) Rectilinear motion - A car moving in straight line. An object is said to be in a rectilinear motion when two objects are moving in a straight... View Article

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