Materials and Components In paramagnetic materials interaction between D. 4 mH
neighbouring dipoles is negligible.
1. Diamond is a paramagnetic material. Inductance is inversely proportional to the core
5. Assertion (A): Atomic number of sodium is 11. length.
A. True
Reason (R): Sodium has a body centred cubic 8. The minority carrier life time and diffusion
B. False
lattice. constant in a semiconducting material are 100 μs
Diamond is diamagnetic. and 100 cm2/s respectively. The diffusion length of
A. Both A and R are true and R is correct
carriers is
2. Which capacitor-store higher amount of energy? explanation of A
A. 0.1 cm
A. Air capacitor B. Both A and R are true but R is not correct
explanation of A B. 0.01 cm
B. Paper capacitor
C. A is true but R is false C. 0.0141 cm
C. Mica capacitor
D. A is false but R is true D. 1 cm
D. Plastic film capacitor
Atomic number is not dependent on lattice Diffusion length = sqrt(Carrier life time x Diffusion
Energy stored is proportional to capacitance and structure. constant) = (100 x 10-6 x 100)0.5 = 0.1 cm.
capacitance is proportional to permittivity.
6. The conductivity of intrinsic semiconductor is 9. Assertion (A): Electronic and Ionic polarization in
3. Above ferroelectric curie temperature, given by a polyatomic gas are independent of temperature.
spontaneous polarization in ferroelectric materials
becomes stronger. A. eni(μp - μn) Reason (R): The orientation polarization is
independent of temperature.
A. True B. eni(μp + μn)
A. Both A and R are true and R is correct
B. False C. ni(μp + μn)
explanation of A
Spontaneous polarization vanishes above ferro- D. ni(μpμn)
B. Both A and R are true but R is not correct
electric Curie temperature. explanation of A
For intrinsic semiconductor, Conductivity =
4. In paramagnetic materials (Electron charge) x (Number of charge C. A is true but R is false
A. permanent magnetic dipoles exist but the carriers) x (Sum of mobilities of holes and
electrons). D. A is false but R is true
interaction between neighbouring dipoles is
negligible Orientation polarization is inversely proportional
7. The core of a coil has a length of 10 cm. The self to temperature.
B. permanent magnetic dipole do not exist inductance is 8 mH. If the core length is doubled,
all other quantities remaining the same, the self 10. Two materials having temperature coefficients
C. permanent magnetic dipoles exist and the of 0.004 and 0.0004 respectively are joined in
inductance will be
interaction between neighbouring dipoles is very series. The overall temperature coefficient is likely
strong A. 32 mH to be
D. permanent magnetic dipole moment may or B. 16 mH A. 0.08 B. 0.04
may not exist
C. 8 mH C. 0.001 D. 0.0001
,The overall temperature coefficient will be less C. A is true but R is false B. Both A and R are true but R is not correct
than 0.004 and more than 0.0004. explanation of A
D. A is false but R is true
11. The number of valence electrons in C. A is true but R is false
Cut in voltage of silicon is higher than that in
pentavalent impurity is
germanium. D. A is false but R is true
A. 5 B. 4 C. 3 D. 1
15. Material which lack permanent magnetic
Imaginary part of ∈r gives rise to absorption
Pentavalent means 5 valence electrons. dipoles are known as
of energy by the material from alternating
12. If the diameter of a wire is doubled, its current A. paramagnetic B. diamagnetic field. Hence current does not lead the
carrying capacity becomes voltage by 90°.
C. ferromagnetic D. ferrimagnetic
A. one-fourth 18. In atomic physics, a state with l = 0 is called p
Diamagnetic materials have no permanent
state.
B. half magnetic diploes.
A. True B. False
C. twice 16. A parallel plate capacitor has its length, width
and separation doubled. It fringing effects are The state with l = 0 is called s state.
D. four times
neglected, to keep the capacitance same, the
dielectric constant must be 19. If a sample of germanium and a sample of
Current carrying capacity depends on area of
silicon have the same impurity density and are kept
cross-section.
A. halved at room temperature
13. The law J = σE, where J is current density, σ is
B. kept the same A. both will have equal value of resistivity
electrical conductivity and E is field strength is
C. doubled B. both will have equal negative resistivity
A. Ohm's law
D. made 4 times C. resistivity of germanium will be higher than that
B. Gauss law
of silicon
C. Ampere's law
. When dimensions are changed, D. resistivity of silicon will be higher than that of
D. Biot-Savart law A become four times and d becomes twice. germanium
It is another form of Ohm's law. Since ∈0 is constant, ∈r must be halved to Resistivity of silicon is more than that of
keep C constant. germanium.
14. Assertion (A): Silicon is less sensitive to
changes in temperature than germanium. 17. Assertion (A): In imperfect capacitors, the 20. When an electric field E is applied to solid and
current does not lead the applied ac voltage by 90°. liquid insulating materials, the internal field Ei
Reason (R): Cut in voltage in silicon is less than that
acting at the location of atom is such that
in germanium. Reason (R): When subjected to ac fields, the
dielectric constant can be expressed as ∈'r - j∈"r. A. Ei = E
A. Both A and R are true and R is correct
explanation of A A. Both A and R are true and R is correct B. Ei > E
explanation of A
B. Both A and R are true but R is not correct C. Ei < E
explanation of A
D. Ei may be equal to or less than E
, The actual field seen by an atom is larger than 25. Assertion (A): Magnetic susceptibility of C. the minority carrier density becomes 4 times
applied field. diamagnetic materials is much less than that of the original value
paramagnetic materials.
21. Which element exhibits the property of D. both the majority and minority carrier
inertia? Reason (R): For diamagnetic as well as densities double
paramagnetic materials, μr is nearly equal to 1.
A. Resistance
A. Both A and R are true and R is correct As the intrinsic carrier concentration is doubled,
B. Capacitance the concentration of both electrons and holes is
explanation of A
doubled.
C. Inductance
B. Both A and R are true but R is not correct
D. Both resistance and inductance explanation of A 28. There is no hysteresis phenomenon is any
dielectric material.
Inductance opposes rise and decay of current. C. A is true but R is false
Hence it has the property of inertia. A. True B. False
D. A is false but R is true
22. For a permanent magnetic material
Hysteresis phenomenon exists in dielectic
Magnetic susceptibility = (μr - 1)H. For
A. the residual induction and coercive field should materials.
diamagnetic and paramagnetic materials
be large magnetic susceptibility is very very small
29. The units of μ0 and μr are
B. the residual induction and coercive field should and μr = 1.
be small A. H/m for both
26. The attraction between the nucleus and
C. area of hysteresis loop should be small valence electron of copper atom is
B. H/m for μr and no units for μ0
D. initial relative permeability should be high A. zero
C. H/m for μ0 and no units for μr
Materials suitable for permanent magnet B. weak
have large hysteresis loop. Hence residual D. Wb/m for μ0 and no units for μr
and coercive field are large. C. strong
μr is only a numeric.
23. In a coaxial cable, braided copper is used for D. either zero or strong
30. In metals the valence electron wave
A. conductor B. shield functions are strongly perturbed by the
The valence electron, in copper atom, can be
presence of neighbouring atoms.
C. dielectric D. jacket easily detached from nucleus.
Braided material is used for shield. A. True B. False
27. If the temperature of an extrinsic
24. The hysteresis phenomenon in ferromagnetic semiconductor is increased so that the intrinsic
In a metal valence electrons are shared by all
materials exists at all temperatures. carrier concentration is doubled, then
atoms.
A. True B. False A. the majority carrier density is doubled
31. For a paramagnetic material, susceptiblity
Hysteresis phenomenon exists below increases with increasing temperature.
B. the minority carrier density is doubled
ferromagnetic curie temperature.
neighbouring dipoles is negligible.
1. Diamond is a paramagnetic material. Inductance is inversely proportional to the core
5. Assertion (A): Atomic number of sodium is 11. length.
A. True
Reason (R): Sodium has a body centred cubic 8. The minority carrier life time and diffusion
B. False
lattice. constant in a semiconducting material are 100 μs
Diamond is diamagnetic. and 100 cm2/s respectively. The diffusion length of
A. Both A and R are true and R is correct
carriers is
2. Which capacitor-store higher amount of energy? explanation of A
A. 0.1 cm
A. Air capacitor B. Both A and R are true but R is not correct
explanation of A B. 0.01 cm
B. Paper capacitor
C. A is true but R is false C. 0.0141 cm
C. Mica capacitor
D. A is false but R is true D. 1 cm
D. Plastic film capacitor
Atomic number is not dependent on lattice Diffusion length = sqrt(Carrier life time x Diffusion
Energy stored is proportional to capacitance and structure. constant) = (100 x 10-6 x 100)0.5 = 0.1 cm.
capacitance is proportional to permittivity.
6. The conductivity of intrinsic semiconductor is 9. Assertion (A): Electronic and Ionic polarization in
3. Above ferroelectric curie temperature, given by a polyatomic gas are independent of temperature.
spontaneous polarization in ferroelectric materials
becomes stronger. A. eni(μp - μn) Reason (R): The orientation polarization is
independent of temperature.
A. True B. eni(μp + μn)
A. Both A and R are true and R is correct
B. False C. ni(μp + μn)
explanation of A
Spontaneous polarization vanishes above ferro- D. ni(μpμn)
B. Both A and R are true but R is not correct
electric Curie temperature. explanation of A
For intrinsic semiconductor, Conductivity =
4. In paramagnetic materials (Electron charge) x (Number of charge C. A is true but R is false
A. permanent magnetic dipoles exist but the carriers) x (Sum of mobilities of holes and
electrons). D. A is false but R is true
interaction between neighbouring dipoles is
negligible Orientation polarization is inversely proportional
7. The core of a coil has a length of 10 cm. The self to temperature.
B. permanent magnetic dipole do not exist inductance is 8 mH. If the core length is doubled,
all other quantities remaining the same, the self 10. Two materials having temperature coefficients
C. permanent magnetic dipoles exist and the of 0.004 and 0.0004 respectively are joined in
inductance will be
interaction between neighbouring dipoles is very series. The overall temperature coefficient is likely
strong A. 32 mH to be
D. permanent magnetic dipole moment may or B. 16 mH A. 0.08 B. 0.04
may not exist
C. 8 mH C. 0.001 D. 0.0001
,The overall temperature coefficient will be less C. A is true but R is false B. Both A and R are true but R is not correct
than 0.004 and more than 0.0004. explanation of A
D. A is false but R is true
11. The number of valence electrons in C. A is true but R is false
Cut in voltage of silicon is higher than that in
pentavalent impurity is
germanium. D. A is false but R is true
A. 5 B. 4 C. 3 D. 1
15. Material which lack permanent magnetic
Imaginary part of ∈r gives rise to absorption
Pentavalent means 5 valence electrons. dipoles are known as
of energy by the material from alternating
12. If the diameter of a wire is doubled, its current A. paramagnetic B. diamagnetic field. Hence current does not lead the
carrying capacity becomes voltage by 90°.
C. ferromagnetic D. ferrimagnetic
A. one-fourth 18. In atomic physics, a state with l = 0 is called p
Diamagnetic materials have no permanent
state.
B. half magnetic diploes.
A. True B. False
C. twice 16. A parallel plate capacitor has its length, width
and separation doubled. It fringing effects are The state with l = 0 is called s state.
D. four times
neglected, to keep the capacitance same, the
dielectric constant must be 19. If a sample of germanium and a sample of
Current carrying capacity depends on area of
silicon have the same impurity density and are kept
cross-section.
A. halved at room temperature
13. The law J = σE, where J is current density, σ is
B. kept the same A. both will have equal value of resistivity
electrical conductivity and E is field strength is
C. doubled B. both will have equal negative resistivity
A. Ohm's law
D. made 4 times C. resistivity of germanium will be higher than that
B. Gauss law
of silicon
C. Ampere's law
. When dimensions are changed, D. resistivity of silicon will be higher than that of
D. Biot-Savart law A become four times and d becomes twice. germanium
It is another form of Ohm's law. Since ∈0 is constant, ∈r must be halved to Resistivity of silicon is more than that of
keep C constant. germanium.
14. Assertion (A): Silicon is less sensitive to
changes in temperature than germanium. 17. Assertion (A): In imperfect capacitors, the 20. When an electric field E is applied to solid and
current does not lead the applied ac voltage by 90°. liquid insulating materials, the internal field Ei
Reason (R): Cut in voltage in silicon is less than that
acting at the location of atom is such that
in germanium. Reason (R): When subjected to ac fields, the
dielectric constant can be expressed as ∈'r - j∈"r. A. Ei = E
A. Both A and R are true and R is correct
explanation of A A. Both A and R are true and R is correct B. Ei > E
explanation of A
B. Both A and R are true but R is not correct C. Ei < E
explanation of A
D. Ei may be equal to or less than E
, The actual field seen by an atom is larger than 25. Assertion (A): Magnetic susceptibility of C. the minority carrier density becomes 4 times
applied field. diamagnetic materials is much less than that of the original value
paramagnetic materials.
21. Which element exhibits the property of D. both the majority and minority carrier
inertia? Reason (R): For diamagnetic as well as densities double
paramagnetic materials, μr is nearly equal to 1.
A. Resistance
A. Both A and R are true and R is correct As the intrinsic carrier concentration is doubled,
B. Capacitance the concentration of both electrons and holes is
explanation of A
doubled.
C. Inductance
B. Both A and R are true but R is not correct
D. Both resistance and inductance explanation of A 28. There is no hysteresis phenomenon is any
dielectric material.
Inductance opposes rise and decay of current. C. A is true but R is false
Hence it has the property of inertia. A. True B. False
D. A is false but R is true
22. For a permanent magnetic material
Hysteresis phenomenon exists in dielectic
Magnetic susceptibility = (μr - 1)H. For
A. the residual induction and coercive field should materials.
diamagnetic and paramagnetic materials
be large magnetic susceptibility is very very small
29. The units of μ0 and μr are
B. the residual induction and coercive field should and μr = 1.
be small A. H/m for both
26. The attraction between the nucleus and
C. area of hysteresis loop should be small valence electron of copper atom is
B. H/m for μr and no units for μ0
D. initial relative permeability should be high A. zero
C. H/m for μ0 and no units for μr
Materials suitable for permanent magnet B. weak
have large hysteresis loop. Hence residual D. Wb/m for μ0 and no units for μr
and coercive field are large. C. strong
μr is only a numeric.
23. In a coaxial cable, braided copper is used for D. either zero or strong
30. In metals the valence electron wave
A. conductor B. shield functions are strongly perturbed by the
The valence electron, in copper atom, can be
presence of neighbouring atoms.
C. dielectric D. jacket easily detached from nucleus.
Braided material is used for shield. A. True B. False
27. If the temperature of an extrinsic
24. The hysteresis phenomenon in ferromagnetic semiconductor is increased so that the intrinsic
In a metal valence electrons are shared by all
materials exists at all temperatures. carrier concentration is doubled, then
atoms.
A. True B. False A. the majority carrier density is doubled
31. For a paramagnetic material, susceptiblity
Hysteresis phenomenon exists below increases with increasing temperature.
B. the minority carrier density is doubled
ferromagnetic curie temperature.
