Physics Questions

The resistance of metallic conductors e.g, platinum, increases with rise of  temperature . The increase in temperature results in a decrease of current which can be recorded in a galvanometer if the conductor is included in an electrical circuit. Thus the temperature can be known; platinum resistance thermometer is used generally for accurate scientific work. When two dissimilar metals are joined at the ends, and these ends are subjected to a difference of temperature, a current flows through the metals. Greater the difference of temperature , greater the current. So the curent strength can form the basis for measuring the difference in temperature. And when one of these temperatures is known, we can calculate the other.

To produce controlled energy i.e energy at a controlled or steady rate, the number of fissions per second must be controlled and maintained at that rate. Excess neutrons should be absorbed by control roads like cadmium.

When traveling in a vacuum, electronic waves from the electromagnetic spectrum all travel at the same speed. Velocity is speed with direction, so they would all travel at the same velocity, realtively speaking. But frequency and wavelength are quite different.

True, Air is a Mixture.

Air is considered as mixture for the following reasons ;

1. Air can be separated into its components like N2, O2 , Argon and CO2 by the process of fractional distillation of liquid air.

2. Air shows the properties of all the gases present in the atmosphere.
For example : Oxygen is good Supporter of combustion. Hence air also is good supporter of combustion.

3. Air does not have a fixed formula.

4. Air has a variable composition because air at different places contains different amount of gases.

5. Heat or Light energy is neither absorbed nor released when air is prepared physical by mixing required amount of gases .

6. Mixture does have fixed boiling Point. It holds good in case of liquid air.

Cohesion refers to attraction between molecules of the same kind while adhesion refers to attraction between different kinds of molecules

A fixture is defined as a device which holds and locates a workpiece and guides and controls one or more cutting tools.

Heat transfer through radiation takes place in form of electromagnetic waves mainly in the infrared region. It depends on nature of the body, its temperature and kind & extent of its surface.