Retentivity is

 701. Band gap of germanium is approximately

A) 0.72 eV
B) 1.1 eV
C) 1.43 eV
D) 2 eV
Ans: A

702. 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

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

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

705. 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

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

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

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

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

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

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

712. 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

713. 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

730. 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

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

732. 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

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

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

735. 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

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

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

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

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

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

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

742. 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

743. 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

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

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

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

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

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

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

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