Q.71)-The device used to change the speed of an electric fan is
  • Amplifier
  • Regulator
  • Switch
  • Rectifier
Q.72)-A transformer works on the principle of
  • Self induction
  • Mutual induction
  • Generator
  • Inverter
Q.73)-Pure water is bad conductor of electricity because it is
  • Feebly ionized
  • Not volatile
  • A very good solvent
  • A non-polar solvent
Q.74)-The nature of fuse wire is
  • High resistance and low melting point
  • High resistance and high melting point
  • Low resistance and high melting point
  • Low resistance and low melting point.
Q.75)-Electric current in a metal wire is due to the flow of
  • Electrons
  • Protons
  • Ions
  • Holes
Q.76)-Which of the following is a good conductor of heat but a bad conductor of electricity?
  • Celluloid
  • Rubber
  • Asbestos
  • Mica
Q.77)-Which of the following is arranged in order of decreasing conductivity?
  • Copper, Aluminium, Steel, Silver
  • Aluminium, Silver, Copper, Steel
  • Copper, Silver, Aluminium, Steel
  • Silver, Copper, Aluminium , Steel
Q.78)-If a copper wire is increased to double its length,its resistance will become
  • Four times
  • One-fourth
  • Double
  • Half
Q.79)-A device which is used to limit the current in an electrical circuit is called a
  • Grid
  • Fuse
  • Hub
  • Conductor
Q.80)-The earth-wire of a cable is connected to
  • The outer metallic body of the appliance
  • The fuse of the appliance
  • The filament of the appliance
  • Short circuit of the appliance