NCERT Solutions

Which of the following are luminous objects?

Mars, Moon, Pole Star, Sun, Venus, Mirror

Match the items in Column A with those in Column B.

\begin{tabular}{|l|l|} \hline Column A & Column B
\hline Pinhole camera & Blocks light completely
\hline Opaque object & The dark region formed behind the object
\hline Transparent object & Forms an inverted image
\hline Shadow & Light passes almost completely through it
\hline \end{tabular}

Sahil, Rekha, Patrick, and Qasima are trying to observe the candle flame through the pipe as shown in Fig. 11.16. Who can see the flame?

Look at the images shown in Fig. 11.17 and select the correct image showing the shadow formation of the boy.

The shadow of a ball is formed on a wall by placing the ball in front of a fixed torch as shown in Fig. 11.18. In scenario (i) the ball is closer to the torch, while in scenario (ii) the ball is closer to the wall. Choose the most accurate representation of the shadows formed in both scenarios from the options provided ( a and b ).

Based on Fig. 11.18, match the position of the torch in Column A with the characteristics of the ball's shadow in Column B.

\begin{tabular}{|l|l|} \hline Column A & Column B
\hline If the torch is close to the ball & The shadow would be smaller
\hline If the torch is far away & The shadow would be larger
\hline If the ball is removed from the set-up & Two shadows would appear on the screen
\hline If two torches are present in the set-up on the left side of the ball & A bright spot would appear on the screen
\hline \end{tabular}

Suppose you view the tree shown in Fig. 11.19 through a pinhole camera. Sketch the outline of the image of the tree formed in the pinhole camera.

Write your name on a piece of paper and hold it in front of a plane mirror such that the paper is parallel to the mirror. Sketch the image. What difference do you notice? Explain the reason for the difference.

Suppose you are given a tube of the shape shown in the Fig. 11.20 and two plane mirrors smaller than the diameter of the tube. Can this tube be used to make a periscope? If yes, mark where you will fix the plane mirrors.

We do not see the shadow on the ground of a bird flying high in the sky. However, the shadow is seen on the ground when the bird swoops near the ground. Think and explain why it is so.