Bihar Board 12th Physics Objective Important Questions Part 2 in English

Bihar Board 12th Physics Objective Important Questions Part 2 in English

BSEB 12th Physics Objective Important Questions Part 2 in English

Question 1.
Tangent law is applicable between the two magnetic force when the angle between them is:
(i) 45°
(ii) 90°
(iii) 0°
(iv) None
Answer:
(ii) 90°

Question 2.
Copper is:
(i) dia magnetic
(ii) ferro magnetic
(iii) para magnetic
(iv) None of the above
Answer:
(i) dia magnetic

Question 3.
The permeability of a certain material is less than 1. Its susceptibility will be:
(i) positive and large
(ii) zero
(iii) positive and small
(iv) negative
Answer:
(iv) negative

Question 4.
SI unit of magnetic pole strength is:
(i) N
(ii) N/Am
(iii) Am
(iv) T
Answer:
(iii) Am

Question 5.
When the magnetic moment increases, time period?
(i) increases
(ii) decreases
(iii) remains unchanged
(iv) None of these
Answer:
(ii) decreases

Question 6.
The apparent dip at a place is always:
(i) less than true dip
(ii) equal to the true dip
(iii) greater than the true dip
(iv) None of these
Answer:
(iii) greater than the true dip

Question 7.
Two lenses of focal length 20 cm. and -40 cm. are in contact. The power of combination will be:
(i) 5D
(ii) 2.5D
(iii) -2.5D
(iv) -5D
Answer:
(ii) 2.5D

Question 8.
Power of a lens of focal length 10 cm. is:
(i) +5D
(ii) -5D
(iii) +10D
(iv) -10D
Answer:
(iii) +10D

Question 9.
A convex lens is immersed in water. Its power:
(i) increases
(ii) decreases
(iii) remains constant
(iv) none of these
Answer:
(ii) decreases

Question 10.
Blue colour of sky is due to the phenomenon of
(i) Refletion
(ii) Refraction
(iii) Scattering
(iv) Dispersion
Answer:
(iii) Scattering

Question 11.
The stars twinkle at night due to:
(i) reflection
(ii) diffraction
(iii) refraction
(iv) stars emitting energy
Answer:
(iii) refraction

Question 12.
A bubble of air inside water appears shining due to:
(i) refraction
(ii) reflection
(iii) diffraction
(iv) total internal reflection
Answer:
(iv) total internal reflection

Question 13.
When a beam of monochromatic light passes from one medium to another, the quantity that does not change?
(i) wave length
(ii) frequency
(iii) velocity
(iv) amplitude
Answer:
(ii) frequency

Question 14.
Air bubble inside water seems to glow due to:
(i) reflection
(ii) refraction
(iii) diffraction
(iv) Total intend reflection
Answer:
(iv) Total intend reflection

Question 15.
Bending of light from the edge of an obstacle is called:
(i) diffraction
(ii) dispersion
(iii) refraction
(iv) reflection
Answer:
(i) diffraction

Question 16.
The bending of a ray of light when it passes from one medium to another medium is called:
(i) diffraction
(ii) dispersion
(iii) refraction
(iv) reflection
Answer:
(iii) refraction

Question 17.
A virtual image larger than the object can be produced by:
(i) convex mirror
(ii) plane mirror
(iii) concave mirror
(iv) concave lens
Answer:
(iii) concave mirror

Question 18.
The image formed by a simple microscope is:
(i) virtual and erect
(ii) virtual and inverted
(iii) real and erect
(iv) real and inverted
Answer:
(i) virtual and erect

Question 19.
In a compound microscope, if f₀ and f_e represent the focal length of the objective and the eye piece respectively then:
(i) f₀ > f_e
(ii) f_e > f₀
(iii) f₀ = f_e
(iv) f₀ = 2f_e
Answer:
(ii) f_e > f₀

Question 20.
When the length of the tube of a microscope is increased its magnifying power:
(i) increases
(ii) decreases
(iii) becomes zero
(iv) remains unchanged
Answer:
(i) increases

Question 21.
The objective of an astronomical telescope must have:
(i) a high power
(ii) a long focal length
(iii) a high refractive index
(iv) a low refractive index.
Answer:
(ii) a long focal length

Question 22.
In fig. there are two covex lenses L₁ & L₂ of focal length F₁ & F₂ respectively. The distance between L₁ & L₂ will be –

(i) F₁
(ii) F₂
(iii) F₁ + F₂
(iv) F₁ – F₂
Answer:
(iii) F₁ + F₂

Question 23.
In an astronomical telescope, the final image obtained is:
(i) real and erect
(ii) real and inverted
(iii) virtual and erect
(iv) virtual and inverted
Answer:
(iv) virtual and inverted

Question 24.
Eyes having short-sightedness defect can see clearly:
(i) object at infinity
(ii) object at far distance
(iii) near by object
(iv) All the objects
Answer:
(iii) near by object

Question 25.
To remedy the long-sight defect, a person has to use:
(i) a concave lens
(ii) a cylindrical lens
(iii) a plane-concave lens
(iv) a convex lens
Answer:
(iv) a convex lens

Question 26.
For normal eye, the least distance of distinct vision is:
(i) 100 cm
(ii) 50 cm
(iii) 250 cm
(iv) 25 cm
Answer:
(iv) 25 cm

Question 27.
To cure old sight defect, it is needed:
(i) Concave lens
(ii) Convex lens
(iii) Cylindrical lens
(iv) Bifocal lens
Answer:
(iv) Bifocal lens

Question 28.
To cure Astigmatism, it is needed:
(i) Convex lens
(ii) Concave lens
(iii) Cylindrical lens
(iv) Bifocal lens
Answer:
(iii) Cylindrical lens

Question 29.
The defect in sight due to difference in curvature in the various surfaces of the cornea is called:
(i) myopia
(ii) hyper metropia
(iii) presbyopia
(iv) astigmatism
Answer:
(iv) astigmatism

Question 30.
Images of an object formed at Ratina is:
(i) imaginary and erect
(ii) imaginary and inverted
(iii) real and inverted
(iv) real and erected
Answer:
(iii) real and inverted

Question 31.
When white light is passed through prism, the minimum deviation will takes place in:
(i) red
(ii) violet
(iii) yellow
(iv) green
Answer:
(i) red

Question 32.
Wavelength of the colour is largest in:
(i) red
(ii) yellow
(iii) violet
(iv) green
Answer:
(i) red

Question 33.
Spectrum of star is:
(i) continuous
(ii) line
(iii) dark line spectrum
(iv) band
Answer:
(iii) dark line spectrum

Question 34.
The Image formed by objective of a compound microscope is:
(i) Virtual & dimineshed
(ii) Real & diminished
(iii) Real & large
(iv) Virtual & large
Answer:
(iii) Real & large

Question 35.
Fraunhofer lines in solar spectra are produced due to:
(i) Absorption of light in chromosphere
(ii) Absorption of light in atmosphere
(iii) Cosmic rays
(iv) None of these
Answer:
(i) Absorption of light in chromosphere

Question 36.
Line spectra is obtained in:
(i) Atomic state
(ii) Molecular state
(iii) Gaseous state
(iv) Liquid state
Answer:
(i) Atomic state

Question 37.
A chromatic combination of two prisms gives:
(i) Deviation without angular dispersion
(ii) Angular dispersion without deviation
(iii) Neither angular dispersion nor deviation
(iv) None of these
Answer:
(i) Deviation without angular dispersion

Question 38.
With rise in wave length of light, the refractive index of a transparent medium
(i) increases
(ii) decreases
(iii) remains unchanged
(iv) None of the above
Answer:
(ii) decreases

Question 39.
Minimum deviation angle of a thin prism is:
(i) (µ – 1)A²
(ii) (µ – 1)A
(iii) (µ + 1)A
(iv) (1 – µ)A
Answer:
(ii) (µ – 1)A

Question 40.
Red colour of sunrise and sunset is due to:
(i) polarisation of light
(ii) colour of sun
(iii) scattering of light
(iv) colour of sky
Answer:
(iii) scattering of light

Question 41.
Primary rainbow is formed due to:
(i) one reflection
(ii) one total internal reflection
(iii) one dispersion
(iv) all of these
Answer:
(ii) one total internal reflection

Question 42.
The velocity of light is maximum in:
(i) air
(ii) glass
(iii) water
(iv) vacuum
Answer:
(iv) vacuum

Question 43.
The velocity of light in a medium depends on:
(i) the intensity of the source
(ii) the frequency of the source
(iii) None of these
Answer:
(ii) the frequency of the source

Question 44.
Nature of light waves is:
(i) transverse
(ii) longitudinal
(iii) some times longitudinal some times transverse
(iv) None of these
Answer:
(i) transverse

Question 45.
Light waves are proved transverse by:
(i) interference
(ii) diffraction
(iii) polarisation
(iv) None
Answer:
(iii) polarisation

Question 46.
The vlocityof light in galss, whose refractive index µg = 1.5 is 2 × 10⁸m/s. In certain liquid the velocity of light is found to be 2.6 × 10⁸ m/s. The refractive index (µc)of the liquid is.
(i) 1.5
(ii) 1.2
(iii) 1
(iv) 2.1
Answer:
(ii) 1.2

Question 47.
Brewster’s law is:
(i) µ = sin i_p
(ii) µ = cos i_p
(iii) µ = sin i_p
(iv) µ = tan² i_p
Answer:
(iii) µ = sin i_p

Question 48.
Precious stones an detected with the help of
(i) ultraviolet rays
(ii) infrared rays
(iii) x-rays
(iv) None of the above
Answer:
(i) ultraviolet rays

Question 49.
Laser beam is:
(i) highly monochromatic
(ii) monochromatic
(iii) heterogeneous in nature
(iv) monochromatic or not depends upon the energy available
Answer:
(i) highly monochromatic

Question 50.
The laser is a source of:
(i) electric current
(ii) sound
(iii) incoherent light
(iv) coherent light
Answer:
(iv) coherent light

Question 51.
Electromagnetic waves are:
(i) longitudinal
(ii) compressional
(iii) transverse
(iv) both transverse and longitudinal
Answer:
(iii) transverse

Question 52.
X-rays or λ = 1A have freq. of:
(i) 3 × 10⁸ Hz
(ii) 3 × 10¹⁸ Hz
(iii) 3 × 10¹⁰ Hz
(iv) 3 × 10¹⁵ Hz
Answer:
(ii) 3 × 10¹⁸ Hz

Question 53.
Cathode rays are:
(i) electrons
(ii) neutrons
(iii) protons
(iv) photons
Answer:
(i) electrons

Question 54.
The molecules of an atom consists of:
(i) protons
(ii) protons and electrons
(iii) protons and neutrons
(iv) α-particles
Answer:
(iii) protons and neutrons

Question 55.
Electron volt is:
(i) unit of charge
(ii) unit of potential difference
(iii) unit of current
(iv) unit of energy
Answer:
(iv) unit of energy

Question 56.
The charge of an electron is equal to:
(i) 1.6 × 10^-1 C
(ii) 1.6 × 10^-9 C
(iii) 1.6 × 10^-19 C
(iv) 1.6 C
Answer:
(iii) 1.6 × 10^-19 C

Question 57.
The size of the nucleus is of the order of:
(i) 10^-13 cm
(ii) 10^-23 cm
(iii) 10^-8 cm
(iv) 10^-10 cm
Answer:
(i) 10^-13 cm

Question 58.
Which one of the following will deflect in electric field
(i) r-rays
(ii) x-rays
(iii) Uv rays
(iv) cathode rays
Answer:
(iv) cathode rays

Question 59.
Work function is the energy required:
(i) to excite the atom
(ii) just to eject electron form the surface
(iii) to produce x-rays
(iv) None of the above
Answer:
(ii) just to eject electron form the surface

Question 60.
Relation between mass and energy is:
(i) E = mc²
(ii) E = mc
(iii) E = mc³
(iv) None of these
Answer:
(i) E = mc²

Question 61.
Chadwick discovered:
(i) radioactivity
(ii) electron
(iii) proton
(iv) neutron
Answer:
(iv) neutron

Question 62.
β-particles are fast moving:
(i) electrons
(ii) positrons
(iii) protons
(iv) neutrons
Answer:
(i) electrons

Question 63.
γ-rays are similar to:
(i) α-rays
(ii) Cathode rays
(iii) X-rays
(iv) None of the above
Answer:
(iii) X-rays

Question 64.
According to maxwell’s hypothesis, a changing electric field gives rise to:
(i) an emf
(ii) Electric current
(iii) Pressure gradient
(iv) magnetic field
Answer:
(iv) magnetic field

Question 65.
The number of protons in an atom of atomic number Z and mass number A is:
(i) Z
(ii) A
(iii) A – Z
(iv) A + Z
Answer:
(i) Z

Question 66.
Phase diff. between electric and magnetic field in e.m. wave is:
(i) Zero
(ii) 90°
(iii) 120°
(iv) 180°
Answer:
(i) Zero

Question 67.
Which has higher frequency in e.m. spectrum?
(i) α-rays
(ii) β-rays
(iii) γ-rays
(iv) cathode rays
Answer:
(iii) γ-rays

Question 68.
Radio activity is associated with:
(i) fusion of nuclei
(ii) the decay of nuclei
(iii) the production of x-rays
(iv) thermionic emission
Answer:
(ii) the decay of nuclei

Question 69.
If T is the temperature of the filament, the thermionic current varies as:
(i) 7
(ii) T^1/2
(iii) T²
(iv) T³
Answer:
(iii) T²

Question 70.
The quantum of light is known as:
(i) photon
(ii) proton
(iii) hyperon
(iv) phonon
Answer:
(i) photon

Question 71.
A thermionic diode is used as:
(i) an amplifier
(ii) an oscillator
(iii) a modulator
(iv) a rectifier
Answer:
(iv) a rectifier

Question 72.
The action of a radio value is based on the principle of:
(i) thermionic emission
(ii) induction
(iii) Lenz’s law
(iv) Ohm’s law
Answer:
(i) thermionic emission

Question 73.
P-N Junction is used for:
(i) the measurement of temperature
(ii) converting A.C. into D.C.
(iii) obtaining higher voltage from low voltage
(iv) amplifying feeble currents.
Answer:
(ii) converting A.C. into D.C.

Question 74.
The number of photons of freq. 1014 Hz in radiation of 6.62 J will be
(i) 10¹⁰
(ii) 10¹⁵
(iii) 10²⁰
(iv) 10²⁵
Answer:
(iii) 10²⁰

Question 75.
According to J.C.Bose, the range of wave length in e.m. wave is:
(i) 1 mm -10 mm
(ii) 25 mm – 50 mm
(iii) 200 mm – 500 mm
(iv) None of these
Answer:
(ii) 25 mm – 50 mm

Question 76.
Ozone layer is situated from the surface of earth:
(i) 40 km – 50 km
(ii) 100 km – 300 km
(iii) 500 km ~ 1000 km
(iv) None of them
Answer:
(i) 40 km – 50 km

Question 77.
Ionosphere is situated from the surface of earth:
(i) 50 km – 80 km
(ii) 200 km – 400 km
(iii) 500 km – 1000 km
(iv) None of them
Answer:
(ii) 200 km – 400 km

Question 78.
The logic symbol

stands for
(i) OR-Gate
(ii) AND gate
(iii) NOR gate
(iv) NAND gate
Answer:
(iii) NOR gate

Question 79.
The height of TV transmission tower is 245 m at a place on the earth. The distance upto which the broadcasting can be send from the tower as-
(ii) 245 m
(i) 245 km
(iii) 50 km
(iv) 112 km
Answer:
(iii) 50 km

Question 80.
For TV Broadcast which type of modulation is used for audio signals?
(i) Amplitude modulation
(ii) Pulse modulation
(iii) Freq. modulation
(iv) None of these
Answer:
(iii) Freq. modulation