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