# Bihar Board 12th Physics Objective Important Questions Part 2

BSEB Bihar Board 12th Physics Important Questions Objective Type Part 2 are the best resource for students which helps in revision.

## Bihar Board 12th Physics Objective Important Questions Part 2

Question 1.
Magnetic field due to current carrying a wire at a distance from it is proportional to:
(i) r
(ii) $$\frac{1}{r}$$
(iii) $$\frac{1}{r^{2}}$$
(iv) r2
(ii) $$\frac{1}{r}$$

Question 2.
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
(iii) cot 2θ

Question 3.
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
(ii) low resistance in parallel

Question 4.
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
(ii) high resistance in series

Question 5.
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
(iv) protect from heavy current

Question 6.
The reln. among the electric field ($$\vec{E}$$), current density $$\vec{J}$$ and resistivity (ρ) is:
(i) $$\vec{E}=\rho \vec{J}$$
(ii) $$\vec{J}=\rho \vec{E}$$
(iii) $$\rho=\rho \vec{E} \cdot \vec{J}$$
(iv) None of these
(i) $$\vec{E}=\rho \vec{J}$$

Question 7.
By using Shunt the range of an ammeter:
(i) is increased
(ii) is decreased
(iii) remains constant
(iv) None
(i) is increased

Question 8.
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
(i) 1 Ohm

Question 9.
The important law governing electromagnetic induction is called:
(i) Newton’s law
(ii) Ohm’s law
(iv) Ampere’s law

Question 10.
If electron velocity is 2$$\hat{i}$$ +3$$\hat{j}$$ and it is subjected to magnetic field of 4$$\hat{k}$$, there its:
(i) path will change
(ii) speed will change
(iii) both (i) and (ii)
(iv) None
(i) path will change

Question 11.
Lenz’s is a consequence of the law of conservation of:
(i) charge
(ii) energy
(iii) mass
(iv) momentum
(ii) energy

Question 12.
Induction coil is an instrument for generating:
(i) large current
(ii) high voltage
(iii) small current
(iv) small voltage
(ii) high voltage

Question 13.
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.
(iv) curved path

Question 14.
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
(iii) electromagnetic induction

Question 15.
The unit of self inductance is:
(i) Weber
(ii) Ohm
(iii) Henry
(iv) None
(iii) Henry

Question 16.
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
(iii) Low voltage to high voltage and vice versa

Question 17.
In the step up transformer:
(i) NS > NP
(ii) NS < NP
(iii) NS = NS
(iv) None of these
(i) NS > NP

Question 18.
The value of ‘I’ given circuit is: (i) 11A
(ii) 3A
(iii) 17A
(iv) -3A
(iv) -3A

Question 19.
A.C. is measured by:
(i) Galvanometer
(ii) moving coil ammeter
(iii) hot wire ammeter
(iv) None of these
(iii) hot wire ammeter

Question 20.
The ratio of r.m.s. value to peak value of A.C. is:
(i) $$\sqrt{2}$$ : 1
(ii) $$\sqrt{2}$$ : 1
(iii) 2 : 1
(iv) 1 : 2
(ii) $$\sqrt{2}$$ : 1

Question 21.
A.C. of 3A is the same as:
(i) 3 Coulomb/sec
(ii) 3 Ohm/meter
(iii) 3 Joule/coulomb
(iv) 3 Watt/second
(i) 3 Coulomb/sec

Question 22.
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.
(ii) Reducing current in A.C. circuit

Question 23.
In ac current changes
(i) only direction
(ii) magnitude only
(iii) both magnitude and direction
(iv) None
(iii) both magnitude and direction

Question 24.
The dynamo works on the principle of:
(i) induced magnetism
(ii) coulomb’s law
(iii) electromagnetic induction
(iv) None of these
(iii) electromagnetic induction

Question 25.
A st. conductor carrying a d.c. of i amp., is split into circualar loop as shown in fig. then the mag. induction at the centre of the loop of radius r meter is (i) 0
(ii) ∞
(iii) $$\frac{\mu_{0} i}{2 r}$$
(iv) $$\frac{\mu_{0}}{2 \pi r}$$
(i) 0

Question 26.
What is the relation between mobility and drift velocity
(i) $$\mu=\frac{v_{d}}{E}$$
(ii) $$\mu=\frac{E}{v_{d}}$$
(iii) µ = E,vd
(iv) $$\mu=\frac{E^{2}}{v_{d}}$$
(i) $$\mu=\frac{v_{d}}{E}$$

Question 27.
Inverse of electrical resistance is called:
(i) Electrical conductivity
(ii) Thermal conductivity
(iii) current
(iv) e.m.f.
(i) Electrical conductivity

Question 28.
Ohm’s law does not obeyed by
(i) insulator
(ii) Semiconductor
(iii) diode
(iv) All of the above
(iv) All of the above

Question 29.
Mean value of A.C. is given by equation:
(i) $$\frac{2}{\Pi} i_{0}$$
(ii) $$\frac{1}{\Pi} i_{0}$$
(iii) $$\frac{\Pi}{2 i_{0}}$$
(iv) $$\frac{i_{0}}{\Pi}$$
(i) $$\frac{2}{\Pi} i_{0}$$

Question 30.
The average Power in A.C. circuit is: irms erms cosΦ

Question 31.
Impedence is a type of:
(i) current
(ii) e.m.f
(iii) Resistance
(iv) Power
(iii) Resistance

Question 32.
The value of torque of a magnetic dipole is
(i) M2B sinθ
(ii) $$\frac{M B}{\sin \theta}$$
(iii) $$\frac{\sin \theta}{M B}$$
(iv) MB sinθ
(iv) MB sinθ

Question 33.
The angle of magnetic dip at the equator is:
(i) 0°
(ii) 90°
(iii) 45°
(iv) 180°
(i) 0°

Question 34.
The angle of magnetic dip at the pole is:
(i) 0°
(ii) 90°
(iii) 45°
(iv) 180°
(ii) 90°

Question 35.
SI unit of magnetic permeability is
(i) Henery
(ii) Weber/m
(iii) Henery/m
(iv) Tesla
(iii) Henery/m

Question 36.
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
(iv) expand

Question 37.
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.
(i) the spin motion of electrons

Question 38.
The unit of magnetic induction is:
(i) Weber amp/m2
(ii) Weber
(iii) Weber/m2
(iv) Weber amp/m
(iii) Weber/m2

Question 39.
Ampere’s circuital law is analogous to
(i) Gravitation law
(ii) Electrostatic coulm’slaw
(iii) Gauss’s theorem
(iv) None of these
(iii) Gauss’s theorem

Question 40.
The ratio of magnetic intensity in end on position and in broad side on position due to small magnet is:
(i) 2 : 1
(ii) 1 : 2
(iii) $$\sqrt{2}$$ : 1
(iv) 1 : $$\sqrt{2}$$
(i) 2 : 1

Question 41.
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
(ii) magnetic potential is zero

Question 42.
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)
(iv) MB (1 – cos θ)

Question 43.
Deflection magnetometer:
(i) measures the absolute value of the magnetic moment
(ii) measures magnetic moment
(iii) compares the magnetic moment
(iv) None of these
(iii) compares the magnetic moment

Question 44.
If be the frequency of a magnetic needle in the earth’s magnetic field (B) then:
(i) n ∝ B
(ii) n2 ∝ β2
(iii) n2 ∝ β2
(iv) n2 ∝ $$\frac{1}{B}$$
(iii) n2 ∝ β2

Question 45.
(i) steel
(ii) soft iron
(iii) air
(iv) a mixture of copper and zinc.