Sorry for taking this long to respond to your questions:
Qn 1. About the production of electricity using different sources of energy and what is required for the exam.
You need to know the energy transformations taking place in each case but you should not be asked any details about the process (diagrams, etc.) in the exam.
Qn 2. About gears in simple machines.
I’m going to teach about gears in the class. And about non-ideal (efficiency < 100%) pulley systems.
Qn 3. About resistivity of an electrolyte.
Resistivity of any material (solid metal or liquid electrolyte or a gas) is defined as the electrical resistance of the material of unit length and unit cross-sectional area.
For example, resistivity of NaCl solution is the resistance that this solution will offer between two electrodes which are 1 m apart and have an area of 1 m2.
Resistivity of an electrolyte does depend on the nature of the electrolyte, on the concentration of ions in the electrolyte and of course, on the temperature.
Qn 4. About high-tension wires.
High-tension wires are wires especially constructed to carry electric currents at very high voltage. So they are used in high-voltage applications, e.g. in heavy industries or in high-energy physics research labs.
Qn 5. About solenoids and coils and qn. 3 (d) from the term-end exam paper.
A coil is not a solenoid. A solenoid is not a coil.
Both are several turns of a wire wound generally over a cylindrical base.
The difference lies in the shape. A coil looks like a loop of thread while a solenoid looks like a spring. A coil is flatter, a solenoid is longer.
Technically, a coil has a diameter larger than its thickness while a solenoid has a thickness (or length) larger than its diameter.
Qn 6. About two-way switches and the double-pole switches.
They are different. A double-pole switch is like two switches mechanically joined together. So using a double-pole switch you can disconnect (or connect) a pair of wires with another pair of wires. An example is the kind that is used as Main Switch in the household circuits to connect (or disconnect) both Live and Neutral wires inside the house with the Live and Neutral wires coming from outside, by a single throw (flip).
A two-way switch is used to connect a wire to any one of a pair of wires. See the kind that is used in staircase switching. Or the one Edison used in his exploration of the thermionic emission from carbon filaments.
Qn 7. About high-tension, low-tension batteries.
I don’t know the story behind it but tension in electricity refers to voltage. So, a high-tension battery is a battery which can provide high emf (potential difference between its electrodes or terminals). The batteries we usually use are 1.5 V to 12 V batteries and these are called low-tension batteries. For a gas to become conducting, it has to be kept at a very low pressure and a very high voltage has to be applied across it. Therefore for thermionic emission in gases, they had to use high-tension batteries.
Qn 8. About the acceleration of the beam by anodes in cathode ray tube.
Anodes are +ve plates in cathode ray tubes. So negatively charged beam (which comprises of electrons) experiences a force towards the anodes and gets accelerated.
Qn 9. About radiations and waves.
Radiations is a loose term associated both with electromagnetic waves and with the particles emitted from radioactive sources. So, alpha, beta and gamma emissions from radioactive nuclei were also called radiations though out of these only gamma emissions are waves. So gamma radiations can be said to have wavelength (in a classical sense) while alpha and beta emissions are streams of particles.
Qn 10. About using lead for protection against radioactive radiations.
Any heavy metal (go far down in the periodic table) is good at absorbing radioactive emissions. Lead is probably the cheapest of them all. That could be the reason why it is so extensively used in safety gear in radioactive establishments.
Qn 11. About deflecting system in cathode ray tube being like a box.
Yes, the X- and Y-plates can be imagined as two pairs of opposite sides in a box.
Qn 12. About thermometer project.
Use ANY design! It should be working, that’s all. DON’T USE MERCURY THOUGH!
Qn 13. About the centre of gravity of a cone. “The centre of gravity of a solid cone lies at a height 1/4 from the base on the axis whereas the centre of gravity of a hollow cone at a height 1/3 from the base. What’s the difference based on?”
A solid cone is “more biased” towards its base in terms of its mass than a hollow cone is. So for a solid cone, the CG gets “pushed down” further towards the base. Does that make sense? Or are you looking for a more rigorous proof/argument?
Qn 14. About drag being a contact force.
It is a contact force. It is not exactly like friction between two solid surfaces. It is a due to what physicists call ‘viscosity’ of fluids, which you can say is a kind of friction or drag force between different layers of a moving fluid. Drag force is different from friction in many ways, one of them being that it is dependent on the relative velocity between different layers while force due to (kinetic/sliding) friction is independent of speed.
Qn 15. About Schrӧdinger’s cat experiment.
Schrӧdinger’s cat experiment is a thought experiment suggested by physicist Erwin Schrӧdinger. It is built around a certain interpretation of quantum physics (called Copenhagen interpretation). You can look at these links to know about it further:The Physics behind Scrӧdinger’s cat Paradox and Wikipedia, of course!