Magnetic Effects of Electric Current — Science STD 10 — Question

What does the divergence of magnetic field lines near the ends of a current carrying straight solenoid indicate?

A student places a candle flame at a distance of about 60 cm from a convex lens of focal length 10 cm and focuses the image of the flame on a screen. After that he gradually moves the flame towards the lens and each time focuses the image on the screen.

1. In which direction-toward or away from the lens, does he move the screen to focus the image?
2. How does the size of the image change?
3. How does the intensity of the image change as the flame moves towards the lens?
4. Approximately for what distance between the flame and the lens, the image formed on the screen is inverted and of the same size?

Give the reaction involved during extraction of zinc from its ore by.

1. Roasting of zinc ore.
2. Calcination of zinc ore.

What processes would you consider essential for maintaining life?

A woman uses a device X made of a common metal for preventing pregnancy. This device works by preventing the implantation of fertilised egg cell (or embryo) in the female organ Y.

1. What are the two names of device X?
2. Name the organ Y.
3. Can this method of contraception protect a woman from acquiring a STD?

How is food transported in plants?

Separate the following into substances having pH values above and below 7. How do these influence litmus paper?

What happens when a rod of zinc metal is dipped into a solution of copper sulphate? Give chemical equation of the reaction involved.

What are the advantages and disadvantages of using nuclear fuel for generating electricity?