Physics (Part-IV) (Railway)

• In symbols, linear momentum p is defined to be p = mv, where m is the mass of the system and v is its velocity.

• The SI unit for momentum is kg . m/s.

• The siemens (symbolized S) is the Standard International (SI) unit of electrical conductance.

• The archaic term for this unit is the mho (ohm spelled backwards).

• The coulomb is the SI unit for a quantity of charge.

• Sound waves hit a diaphragm that vibrates, moving a magnet near a coil.

• In a condenser microphone, the incoming sound vibrates one plate of a capacitor.

• The varying capacitance is converted into a corresponding electrical signal.

• The udometer is an instrument to measure a quantity of rainfall in inches or centimeters.

• Ammeter is used for measuring either direct or alternating electric current, in amperes.

• A hygrometer is a device used to measure humidity.

• A decibel is a logarithmic value to the base 10.

• If the balance is disturbed, then earth would get progressively warmer or cooler with each passing year.

• These seismic waves, which move through the Earth's molten core, can cause destruction on the surface by damaging structures, warping roads and bridges and injuring living things.

• Because the magnetic south pole of the earth lies in the geographical north direction and the magnetic north pole of the earth lies in the geographical south direction.

• Humidity is the measure of the amount of moisture in the air.

• A psychrometer is an example of a hygrometer.