Electromagnetic Waves — Physics STD 12 Science — Question

A thin converging lens is formed with one surface convex and the other plane. Does the position of image depend on whether the convex surface or the plane surface faces the object?

Two spherical bobs, one metallic and the other of glass, of the same size are allowed to fall freely from the same height above the ground. Which of the two would reach earlier and why?

In a transistor:

1. The emitter has the least concentration of impurity.
2. The collector has the least concentration of impurity.
3. The base has the least concentration of impurity.
4. All the three regions have equal concentrations of impurity.

A one meter long glass tube is open at both ends. One end of the tube is dipped into a mercury cup, the tube is kept vertical and the air is pumped out of the tube by connecting the upper end to a suction pump. Can mercury be pulled up into the pump by this process?

Special devices, like the klystron valve or the magnetron valve, are used for production of electromagnetic waves. Name the waves and also write one of their applications.

Can we have a single north pole? A single south pole?

A capacitor has capacitance C. Is this information sufficient to know what maximum charge the capacitor can contain? If yes, what is this charges? If no, what other information is needed?

Which characteristic of electromagnetic waves it is assumed that light waves are electromagnetic?

A barometer tube reads 76cm of mercury. If the tube is gradually inclined keeping the open end immersed in the mercury reservoir, will the length of mercury column be 76cm, more than 76cm or less than 76cm?