Light — Science STD 7 — Question

During sunny day, a pool of water appears to lie on the road some distance ahead. What type of image (virtual or real) do we see?

What could be the nature of the solution if there is no change observed when a blue litmus paper is dipped in a solution?

When the opaque object was a shiny object like a polished steel plate, I got a shadow on the screen, but I also saw that there was a bright spot of light on the wall on the opposite side. Why was it so?

Melting of wax is a change, where a solid changes to liquid state. Give one more such change, which you observe in your surroundings.

On what factors does the heat produced in a wire depend?

We are advised to use an umbrella when you go out in the sun. Comment.

Give an example of oscillatory motion.

What do you mean by an electric circuit?

What is the basic unit of speed?

What is a virtual image? Give one situation, where a virtual image is formed.