Hall effect can determine

 751. Soft magnetic materials are characterized by

A) Low coercivity
B) High coercivity
C) High resistivity
D) Low permeability
Ans: A

752. Hard magnetic materials are used for
A) Permanent magnets
B) Transformer cores
C) Electromagnets
D) Switches
Ans: A

753. Ferrites are
A) Ceramic magnetic materials
B) Metallic conductors
C) Semiconductors
D) Insulators only
Ans: A

754. Soft ferrites are commonly used for
A) High-frequency transformer cores
B) Permanent magnets
C) Switches
D) Motors
Ans: A

755. Hard ferrites are used for
A) Permanent magnets
B) Transformer cores
C) High-frequency applications
D) Conductors
Ans: A

756. Dielectric materials store energy in the form of
A) Electric field
B) Magnetic field
C) Thermal energy
D) Mechanical energy
Ans: A

757. Mica is used in capacitors because of
A) High dielectric strength
B) High conductivity
C) Low resistivity
D) Ferromagnetic property
Ans: A

758. Quartz is used in oscillators because of
A) Piezoelectric effect
B) Magnetic effect
C) Thermal property
D) Conductivity
Ans: A

759. Piezoelectric materials generate voltage when subjected to
A) Mechanical stress
B) Heat
C) Electric current
D) Magnetic field
Ans: A

760. Band gap of silicon at 300 K is
A) 1.1 eV
B) 0.72 eV
C) 1.43 eV
D) 2 eV
Ans: A

761. Band gap of germanium is
A) 0.72 eV
B) 1.1 eV
C) 1.43 eV
D) 2 eV
Ans: A

762. Intrinsic semiconductors have
A) Equal number of electrons and holes
B) More electrons than holes
C) More holes than electrons
D) No carriers
Ans: A

763. N-type semiconductors have
A) Electrons as majority carriers
B) Holes as majority carriers
C) Neutral carriers
D) No carriers
Ans: A

764. P-type semiconductors have
A) Holes as majority carriers
B) Electrons as majority carriers
C) Neutral carriers
D) No carriers
Ans: A

765. The intrinsic carrier concentration of silicon at 300 K is
A) 1.5×10¹⁰ cm⁻³
B) 2.5×10¹³ cm⁻³
C) 10¹² cm⁻³
D) 10⁸ cm⁻³
Ans: A

766. Doping increases
A) Conductivity
B) Resistivity
C) Coercivity
D) Retentivity
Ans: A

767. Donor impurities in silicon create
A) N-type semiconductor
B) P-type semiconductor
C) Conductor
D) Insulator
Ans: A

768. Acceptor impurities in silicon create
A) P-type semiconductor
B) N-type semiconductor
C) Conductor
D) Insulator
Ans: A

769. Hall effect can determine
A) Type of semiconductor
B) Carrier concentration
C) Magnetic field
D) All of these
Ans: D

770. Drift current depends on
A) Carrier concentration, mobility, and electric field
B) Electric field only
C) Temperature
D) Pressure
Ans: A

771. Diffusion current occurs due to
A) Carrier concentration gradient
B) Electric field
C) Magnetic field
D) Pressure
Ans: A

772. Electron mobility in silicon is approximately
A) 1350 cm²/V·s
B) 450 cm²/V·s
C) 1000 cm²/V·s
D) 2000 cm²/V·s
Ans: A

773. Hole mobility in silicon is approximately
A) 450 cm²/V·s
B) 1350 cm²/V·s
C) 800 cm²/V·s
D) 1500 cm²/V·s
Ans: A

774. Electrical resistivity of metals increases with
A) Temperature
B) Decrease in temperature
C) Constant temperature
D) Magnetic field
Ans: A

775. Electrical resistivity of semiconductors decreases with
A) Temperature
B) Decrease in temperature
C) Constant temperature
D) Pressure
Ans: A

776. Thermal conductivity of metals is mainly due to
A) Free electrons
B) Phonons
C) Lattice vibrations
D) Ions
Ans: A

777. Electrical strain gauges work on
A) Variation of resistance with strain
B) Piezoelectric effect
C) Magnetic effect
D) Thermal conductivity
Ans: A

778. Electrical conductivity σ and resistivity ρ are related by
A) σ = 1/ρ
B) σ = ρ
C) σ = ρ²
D) σ = √ρ
Ans: A

779. Retentivity is
A) Ability to retain magnetization
B) Ability to resist current
C) Permeability
D) Susceptibility
Ans: A

780. Coercivity is
A) Reverse field required to demagnetize
B) Permeability
C) Magnetic flux density
D) Conductivity
Ans: A

781. Soft magnetic materials have
A) Low coercivity
B) High coercivity
C) High resistivity
D) Low permeability
Ans: A

782. Hard magnetic materials have
A) High coercivity
B) Low coercivity
C) Zero permeability
D) Low resistivity
Ans: A

783. Ferrites are
A) Ceramic magnetic materials
B) Metallic conductors
C) Semiconductors
D) Insulators only
Ans: A

784. Soft ferrites are commonly used for
A) High-frequency transformer cores
B) Permanent magnets
C) Switches
D) Motors
Ans: A

785. Hard ferrites are used for
A) Permanent magnets
B) Transformer cores
C) High-frequency applications
D) Conductors
Ans: A

786. Dielectric materials store energy in the form of
A) Electric field
B) Magnetic field
C) Thermal energy
D) Mechanical energy
Ans: A

787. Mica is used in capacitors because of
A) High dielectric strength
B) High conductivity
C) Low resistivity
D) Ferromagnetic property
Ans: A

788. Quartz is used in oscillators because of
A) Piezoelectric effect
B) Magnetic effect
C) Thermal property
D) Conductivity
Ans: A

789. Piezoelectric materials generate voltage when subjected to
A) Mechanical stress
B) Heat
C) Electric current
D) Magnetic field
Ans: A

790. Band gap of silicon at 300 K is
A) 1.1 eV
B) 0.72 eV
C) 1.43 eV
D) 2 eV
Ans: A

791. Band gap of germanium is
A) 0.72 eV
B) 1.1 eV
C) 1.43 eV
D) 2 eV
Ans: A

792. Intrinsic semiconductors have
A) Equal number of electrons and holes
B) More electrons than holes
C) More holes than electrons
D) No carriers
Ans: A

793. N-type semiconductors have
A) Electrons as majority carriers
B) Holes as majority carriers
C) Neutral carriers
D) No carriers
Ans: A

794. P-type semiconductors have
A) Holes as majority carriers
B) Electrons as majority carriers
C) Neutral carriers
D) No carriers
Ans: A

795. The intrinsic carrier concentration of silicon at 300 K is
A) 1.5×10¹⁰ cm⁻³
B) 2.5×10¹³ cm⁻³
C) 10¹² cm⁻³
D) 10⁸ cm⁻³
Ans: A

796. Doping increases
A) Conductivity
B) Resistivity
C) Coercivity
D) Retentivity
Ans: A

797. Donor impurities in silicon create
A) N-type semiconductor
B) P-type semiconductor
C) Conductor
D) Insulator
Ans: A

798. Acceptor impurities in silicon create
A) P-type semiconductor
B) N-type semiconductor
C) Conductor
D) Insulator
Ans: A

799. Hall effect can determine
A) Type of semiconductor
B) Carrier concentration
C) Magnetic field
D) All of these
Ans: D

800. Drift current depends on
A) Carrier concentration, mobility, and electric field
B) Electric field only
C) Temperature
D) Pressure
Ans: A