Bihar Board 12th Physics Objective Important Questions Part 1 in English

Bihar Board 12th Physics Objective Important Questions Part 1 in English

BSEB 12th Physics Objective Important Questions Part 1 in English

Question 1.
Value of 1 eV is:
(i) 2 × 10^-18J
(ii) 1.6 × 10^-13J
(iii) 1.6 × 10^-19J
(iv) 3.2 × 10^-19J
Answer:
(iii) 1.6 × 10^-19J

Question 2.
Two copper sphere of same radii, one hollow and the other solid are charged to the same potential. Which will hold more charge?
(i) Solid sphere
(ii) Hollow sphere
(iii) Both will hold equal charge
(iv) Nothing can be predicted.
Answer:
(iii) Both will hold equal charge

Question 3.
Which of the following is vector?
(i) charge
(ii) capacity
(iii) electric intensity
(iv) none
Answer:
(iii) electric intensity

Question 4.
Potential inside hollow spherical shell will he:
(i) Zero
(ii) infinite
(iii) +ve and uniform
(iv) -ve and uniform
Answer:
(iii) +ve and uniform

Question 5.
A soap bubble is given some charge. Its radius is:
(i) increases
(ii) decrease
(iii) remain unchanged
(iv) increase or decrease depending on the nature of the charge
Answer:
(i) increases

Question 6.
Electron volt measures:
(i) charge
(ii) voltage
(iii) current
(iv) energy
Answer:
(iv) energy

Question 7.
Equipotential surface and electric lines of forces:
(i) Cut each at 0°
(ii) Cut each at 90°
(iii) do not cut each other
(iv) may cut at any angle
Answer:
(ii) Cut each at 90°

Question 8.
Which of the following is Scalar quantity:
(i) Electric flux
(ii) Electric intensity
(iii) Electric potential
(iv) Electric dipole moment
Answer:
(iii) Electric potential

Question 9.
Two point charges + 3µc & + 8µc repel each other with a rorce or 40N. If a charge of – 5µc is added to each of then, them force between then will be
(i) +10 N
(ii) + 20 N
(iii) -2 N
(iv) -10 N
Answer:
(iv) -10 N

Question 10.
When a high energy UV photon beam enters an electric field it will be
(i) accelerated
(ii) retarded
(iii) undefected
(iv) None of these
Answer:
(iii) undefected

Question 11.
What is function of capacitor?
(i) To increases capacity
(ii) To decreases capacity
(iii) Neither increase nor decrease capacity
Answer:
(i) To increases capacity

Question 12.
Unit of capacity of a condenser is:
(i) Volt
(ii) Newton
(iii) Faraday
(iv) Ampere
Answer:
(iii) Faraday

Question 13.
Charge distribution causes:
(i) Loss of energy
(ii) Increase in energy
(iii) Remains constant
(iv) None of these
Answer:
(i) Loss of energy

Question 14.
A dielectric substance in which the dipolo meant of a molecule is zero is called
(i) polar
(ii) none polar
(iii) both
(iv) none of these
Answer:
(i) polar

Question 15.
SI unit of electric dipole moment is:
(i) debye
(ii) C-m
(iii) V-m
(iv) N-m
Answer:
(ii) C-m

Question 16.
In a parallel plate air condenser, air is replaced by a medium of higher dielectric constant. The capacity of the condenser will:
(i) increase
(ii) decrease
(iii) not change
(iv) become zero
Answer:
(i) increase

Question 17.
Relative permittivity of a material is always greater than:
(i) Zero
(ii) 1
(iii) 0.5
(iv) 2
Answer:
(ii) 1

Question 18.
The point charges Q & -2Q are placed at same distance apart. It the electric field at the location of Q is E, then the field at the location of -2Q will be
(i) -E/2
(ii) -3E/2
(iii) -E
(iv) -2E
Answer:
(i) -E/2

Question 19.
Van de Graff generator is machine to generate:
(i) high current
(ii) high voltage
(iii) both high current and high voltage
(iv) both small current and small voltage
Answer:
(ii) high voltage

Question 20.
The algebraic sum of the current at a point in an electrical circuit is:
(i) zero
(ii) infinite
(iii) positive
(iv) negative
Answer:
(i) zero

Question 21.
1 micro ampere of current is formed by:
(i) 1.25 × 10¹² electrons
(ii) 5.25 × 10¹² electrons
(iii) 6.25 × 10¹² electrons
(iv) 8.25 × 10¹² electrons
Answer:
(iii) 6.25 × 10¹² electrons

Question 22.
The resistance in an electrical circuit under constant potential difference is halved the heat generated becomes:
(i) half
(ii) double
(iii) four times
(iv) remains the same
Answer:
(ii) double

Question 23.
When the current through an electric bulb is increased by 1 % the power is increased by?
(i) nearly 2%
(ii) 1%
(iii) 0.01%
(iv) 4%
Answer:
(i) nearly 2%

Question 24.
25 watt and 100 watt bulb are connected in series:
(i) 25 watt bulb will be more intense
(ii) 100 watt bulb will be more intense
(iii) both the bulbs will be equally intense
(iv) None of these are correct
Answer:
(i) 25 watt bulb will be more intense

Question 25.
Watt is equal to:
(i) ohm × Ampere
(ii) volt × ohm
(iii) ampere × Joule
(iv) volt × ampere
Answer:
(iv) volt × ampere

Question 26.
kWh (killo Watt hour) is unit of:
(i) energy
(ii) power
(iii) Electricity
(iv) Polestrength
Answer:
(i) energy

Question 27.
The e.m.f. of a cell is measured by:
(i) a voltmeter
(ii) a potentiometer
(iii) an ammeter
(iv) a galvanometer
Answer:
(ii) a potentiometer

Question 28.
The property of a circuit which converts electrical energy into heat is called:
(i) current
(ii) voltage
(iii) magnetism
(iv) resistance
Answer:
(iv) resistance

Question 29.
The potential of electric field produced by a point charge at a point(x,y,z) is given V = 3x² + 5, wher x,y,z are in meters and v is in volt. The intensity at a point (-2, 1, 0) is
(i) +17Vm^-1
(ii) -17Vm^-1
(iii) +12Vm^-1
(iv) -12V/m
Answer:
(iii) +12Vm^-1

Question 30.
Thermocouple is a device which changes-
(i) electrical energy into heat energy
(ii) mechanical energy into heat energy
(iii) heat energy into electric energy
(iv) kinetic energy into heat energy
Answer:
(iii) heat energy into electric energy

Question 31.
When electric current is allowed to flow through the junction of two dissimilar metal wires heat is evolved or absorbed at the junction. This effect is known as?
(i) Joule’s effect
(ii) Peltier effect
(iii) Seebeck effect
(iv) Thomson effect
Answer:
(ii) Peltier effect

Question 32.
The unit of peltier coefficient is:
(i) Ampere
(ii) Joule
(iii) Coulomb
(iv) Volt
Answer:
(iv) Volt

Question 33.
Coulomb is equal to:
(i) volt/sec.
(ii) amp/sec.
(iii) volt × sec.
(iv) amp. × sec.
Answer:
(iv) amp. × sec.

Question 34.
Capacity of an accumulator is measured in:
(i) watt hour
(ii) volt hour
(iii) coulomb hour
(iv) ampere hour
Answer:
(iv) ampere hour

Question 35.
Ampere-hour (Ah) is unit of
(i) power
(ii) charge
(iii) energy
(iv) pot. diff.
Answer:
(ii) charge

Question 36.
The electro chemical equivalent of a substance is defined as the mass of ions liberated by the passage of:
(i) 1 A per minute
(ii) 1 A per hour
(iii) 1 A per second
(iv) 1 A per half second
Answer:
(iii) 1 A per second

Question 37.
Ampere hour is the unit of:
(i) Power
(ii) Energy
(iii) Resistance
(iv) Capacity of a storage cell
Answer:
(iv) Capacity of a storage cell

Question 38.
Fuse wire is made of
(i) nichrome
(ii) Tonguston
(iii) Alloy of lead & tin
(iv) fused glass
Answer:
(iii) Alloy of lead & tin

Question 39.
In for V ~ I graph for a conductor at temp. T₁ & T₂ is shown (T₂ – T₁) is proportional to

(i) cos 2θ
(ii) sin 2θ
(iii) cot 2θ
(iv) tan 2θ
Answer:
(iii) cot 2θ

Question 40.
A galvanometer or voltmeter can be converted into an ammeter by connecting:
(i) high resistance in parallel
(ii) low resistance in parallel
(iii) high resistance in series
(iv) low resistance in series
Answer:
(ii) low resistance in parallel

Question 41.
A galvanometer or ammeter can be converted into a voltmeter by connecting:
(i) high resistance in parallel
(ii) high resistance in series
(iii) low resistance in parallel
(iv) low resistance in series
Answer:
(ii) high resistance in series

Question 42.
Shunt is used with a galvanometer to:
(i) increase its capacity sensitivity
(ii) increase its range
(iii) increase its resistance
(iv) protect from heavy current
Answer:
(iv) protect from heavy current

Question 43.
By using Shunt the range of an ammeter:
(i) is increased
(ii) is decreased
(iii) remains constant
(iv) None
Answer:
(i) is increased

Question 44.
Three equal resistance each of 3 Ohm resistance are connected in parallel their equivalent resistance is?
(i) 1 Ohm
(ii) 3 Ohm
(iii) 9 Ohm
(iv) None of these
Answer:
(i) 1 Ohm

Question 45.
The important law governing electromagnetic induction is called:
(i) Newton’s law
(ii) Ohm’s law
(iii) Faraday’s law
(iv) Ampere’s law
Answer:
(iii) Faraday’s law

Question 46.
Lenz’s is a consequence of the law of conservation of:
(i) charge
(ii) energy
(iii) mass
(iv) momentum
Answer:
(ii) energy

Question 47.
Induction coil is an instrument for generating:
(i) large current
(ii) high voltage
(iii) small current
(iv) small voltage
Answer:
(ii) high voltage

Question 48.
The motion of free electrons in between two successive collisions with the atoms/ions follows:
(i) a straight path
(ii) circular path
(iii) elliptical path
(iv) curved path.
Answer:
(iv) curved path

Question 49.
The working of an induction coil is based on the principle of:
(i) magnetic induction
(ii) electric induction
(iii) electromagnetic induction
(iv) None of these
Answer:
(iii) electromagnetic induction

Question 50.
The unit of self inductance is:
(i) Weber
(ii) Ohm
(iii) Henry
(iv) None
Answer:
(iii) Henry

Question 51.
Transformer is used to convert:
(i) A.C. into D.C.
(ii) D.C. into A.C.
(iii) Low voltage to high voltage and vice versa
(iv) None of these
Answer:
(iii) Low voltage to high voltage and vice versa

Question 52.
In the step up transformer:
(i) N_S > N_P
(ii) N_S < N_P
(iii) N_S = N_S
(iv) None of these
Answer:
(i) N_S > N_P

Question 53.
The value of ‘I’ given circuit is:

(i) 11A
(ii) 3A
(iii) 17A
(iv) -3A
Answer:
(iv) -3A

Question 54.
A.C. is measured by:
(i) Galvanometer
(ii) moving coil ammeter
(iii) hot wire ammeter
(iv) None of these
Answer:
(iii) hot wire ammeter

Question 55.
A.C. of 3A is the same as:
(i) 3 Coulomb/sec
(ii) 3 Ohm/meter
(iii) 3 Joule/coulomb
(iv) 3 Watt/second
Answer:
(i) 3 Coulomb/sec

Question 56.
Choke coil is used in:
(i) Reducing current in D.C. circuit
(ii) Reducing current in A.C. circuit
(iii) Changing A.C. into D.C.
(iv) Changing D.C. into A.C.
Answer:
(ii) Reducing current in A.C. circuit

Question 57.
In ac current changes
(i) only direction
(ii) magnitude only
(iii) both magnitude and direction
(iv) None
Answer:
(iii) both magnitude and direction

Question 58.
The dynamo works on the principle of:
(i) induced magnetism
(ii) coulomb’s law
(iii) electromagnetic induction
(iv) None of these
Answer:
(iii) electromagnetic induction

Question 59.
Inverse of electrical resistance is called:
(i) Electrical conductivity
(ii) Thermal conductivity
(iii) current
(iv) e.m.f.
Answer:
(i) Electrical conductivity

Question 60.
Ohm’s law does not obeyed by
(i) insulator
(ii) Semiconductor
(iii) diode
(iv) All of the above
Answer:
(iv) All of the above

Question 61.
Impedence is a type of:
(i) current
(ii) e.m.f
(iii) Resistance
(iv) Power
Answer:
(iii) Resistance

Question 62.
The angle of magnetic dip at the equator is:
(i) 0°
(ii) 90°
(iii) 45°
(iv) 180°
Answer:
(i) 0°

Question 63.
The angle of magnetic dip at the pole is:
(i) 0°
(ii) 90°
(iii) 45°
(iv) 180°
Answer:
(ii) 90°

Question 64.
SI unit of magnetic permeability is
(i) Henery
(ii) Weber/m
(iii) Henery/m
(iv) Tesla
Answer:
(iii) Henery/m

Question 65.
A current carrying loop is packed in x – y plane and a mag. field is switched in z-axis. The loop will

(i) move towards +ve axis
(ii) contract
(iii) move towards – x
(iv) expand
Answer:
(iv) expand

Question 66.
The cause of magnetism of a magnetic substance is:
(i) the spin motion of electrons
(ii) the pole star
(iii) the particle of the substance
(iv) the sun and the moon.
Answer:
(i) the spin motion of electrons

Question 67.
The unit of magnetic induction is:
(i) Weber amp/m²
(ii) Weber
(iii) Weber/m²
(iv) Weber amp/m
Answer:
(iii) Weber/m²

Question 68.
Ampere’s circuital law is analogous to
(i) Gravitation law
(ii) Electrostatic coulm’slaw
(iii) Gauss’s theorem
(iv) None of these
Answer:
(iii) Gauss’s theorem

Question 69.
At broad side on position of a bar magnet:
(i) magnetic field is zero
(ii) magnetic potential is zero
(iii) field and potential both are zero
(iv) None of these
Answer:
(ii) magnetic potential is zero

Question 70.
Work done in rotating a magnet of magnetic moment M in a magnetic field B is given by:
(i) MB sin θ
(ii) MB(1 – sin θ)
(iii) MB cos θ
(iv) MB (1 – cos θ)
Answer:
(iv) MB (1 – cos θ)

Question 71.
Deflection magnetometer:
(i) measures the absolute value of the magnetic moment
(ii) measures magnetic moment
(iii) compares the magnetic moment
(iv) None of these
Answer:
(iii) compares the magnetic moment

Question 72.
An electromagnet is made of:
(i) steel
(ii) soft iron
(iii) air
(iv) a mixture of copper and zinc.
Answer:
(ii) soft iron

Question 73.
SI unit of magnetic flux is
(i) ohm
(ii) Weber
(iii) Tesla
(iv) none
Answer:
(ii) Weber