# Bihar Board 12th Physics Objective Important Questions Part 1

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## Bihar Board 12th Physics Objective Important Questions Part 1

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
(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.
(iii) Both will hold equal charge

Question 3.
Unit of electric field intensity is:
(i) $$\frac{n}{m}$$
(ii) $$\frac{v}{m}$$
(iii) $$\frac{v}{m^{2}}$$
(iv) $$\frac{d y n e}{c m^{2}}$$
(ii) $$\frac{v}{m}$$

Question 4.
Which of the following is vector?
(i) charge
(ii) capacity
(iii) electric intensity
(iv) none
(iii) electric intensity

Question 5.
Potential inside hollow spherical shell will he:
(i) Zero
(ii) infinite
(iii) +ve and uniform
(iv) -ve and uniform
(iii) +ve and uniform

Question 6.
Intensity of electric field (E) and potential (v) is related as:
(i) $$v=\frac{d E}{d r}$$
(ii) $$v=\frac{-d E}{d r}$$
(iii) $$E=\frac{-d v}{d r}$$
(iv) $$E=\frac{d v}{d r}$$
(iii) $$E=\frac{-d v}{d r}$$

Question 7.
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
(i) increases

Question 8.
Electron volt measures:
(i) charge
(ii) voltage
(iii) current
(iv) energy
(iv) energy

Question 9.
Unit of electric potential is:
(i) $$\frac{J}{c}$$
(ii) $$\frac{J^{2}}{c}$$
(iii) $$\frac{J}{c^{2}}$$
(iv) $$\frac{V}{m}$$
(i) $$\frac{J}{c}$$

Question 10.
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
(ii) Cut each at 90°

Question 11.
Which of the following is Scalar quantity:
(i) Electric flux
(ii) Electric intensity
(iii) Electric potential
(iv) Electric dipole moment
(iii) Electric potential

Question 12.
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
(iv) -10 N

Question 13.
When a high energy UV photon beam enters an electric field it will be
(i) accelerated
(ii) retarded
(iii) undefected
(iv) None of these
(iii) undefected

Question 14.
Electric dipole moment is equal to:
(i) $$\vec{P}=2 l \vec{Q}$$
(ii) $$\vec{P}=\frac{2 l}{\vec{Q}}$$
(iii) $$\vec{P}=\frac{\vec{Q}}{2 l}$$
(iv) $$\vec{P}=2 l \vec{Q}^{2}$$
(i) $$\vec{P}=2 l \vec{Q}$$

Question 15.
What is function of capacitor?
(i) To increases capacity
(ii) To decreases capacity
(iii) Neither increase nor decrease capacity
(i) To increases capacity

Question 16.
Energy stored in a capacitor, is equal to:
(i) $$\frac{1}{2}$$cv
(ii) $$\frac{1}{2}$$c2v
(iii) $$\frac{1}{2}$$cv2
(iv) $$\frac{1}{2} \frac{c^{2}}{v}$$
(iii) $$\frac{1}{2}$$cv2

Question 17.
Unit of capacity of a condenser is:
(i) Volt
(ii) Newton
(iv) Ampere

Question 18.
Equivalent capacitance of two condenser c1 and c2 in parallel connection is:
(i) c1 – c2
(ii) c1 + c2
(iii) c2 – c1
(iv) $$\frac{c_{1} c_{2}}{c_{1}+c_{2}}$$
(ii) c1 + c2

Question 19.
Charge distribution causes:
(i) Loss of energy
(ii) Increase in energy
(iii) Remains constant
(iv) None of these
(i) Loss of energy

Question 20.
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
(i) polar

Question 21.
SI unit of electric dipole moment is:
(i) debye
(ii) C-m
(iii) V-m
(iv) N-m
(ii) C-m

Question 22.
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
(i) increase

Question 23.
Relative permittivity of a material is always greater than:
(i) Zero
(ii) 1
(iii) 0.5
(iv) 2
(ii) 1

Question 24.
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
(i) -E/2

Question 25.
If E is the electric field intensity of an electrostatic field, then the electro space energy density is proportional to-
(i) E
(ii) E2
(iii) $$\frac{1}{E^{2}}$$
(iv) E3
(iii) $$\frac{1}{E^{2}}$$

Question 26.
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
(ii) high voltage

Question 27.
The algebraic sum of the current at a point in an electrical circuit is:
(i) zero
(ii) infinite
(iii) positive
(iv) negative
(i) zero

Question 28.
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
(iii) 6.25 × 1012 electrons

Question 29.
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
(ii) double

Question 30.
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%
(i) nearly 2%

Question 31.
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
(i) 25 watt bulb will be more intense

Question 32.
Watt is equal to:
(i) ohm × Ampere
(ii) volt × ohm
(iii) ampere × Joule
(iv) volt × ampere
(iv) volt × ampere

Question 33.
kWh (killo Watt hour) is unit of:
(i) energy
(ii) power
(iii) Electricity
(iv) Polestrength
(i) energy

Question 34.
The e.m.f. of a cell is measured by:
(i) a voltmeter
(ii) a potentiometer
(iii) an ammeter
(iv) a galvanometer
(ii) a potentiometer

Question 35.
The property of a circuit which converts electrical energy into heat is called:
(i) current
(ii) voltage
(iii) magnetism
(iv) resistance
(iv) resistance

Question 36.
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
(iii) +12Vm-1

Question 37.
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
(iii) heat energy into electric energy

Question 38.
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
(ii) Peltier effect

Question 39.
The unit of peltier coefficient is:
(i) Ampere
(ii) Joule
(iii) Coulomb
(iv) Volt
(iv) Volt

Question 40.
Coulomb is equal to:
(i) volt/sec.
(ii) amp/sec.
(iii) volt × sec.
(iv) amp. × sec.
(iv) amp. × sec.

Question 41.
Capacity of an accumulator is measured in:
(i) watt hour
(ii) volt hour
(iii) coulomb hour
(iv) ampere hour
(iv) ampere hour

Question 42.
Ampere-hour (Ah) is unit of
(i) power
(ii) charge
(iii) energy
(iv) pot. diff.
(ii) charge

Question 43.
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
(iii) 1 A per second

Question 44.
Ampere hour is the unit of:
(i) Power
(ii) Energy
(iii) Resistance
(iv) Capacity of a storage cell
(iv) Capacity of a storage cell

Question 45.
(i) nichrome
(ii) Tonguston
(iii) Alloy of lead & tin
(iv) fused glass
(i) $$\frac{\mu_{0} n i}{2 r}$$
(ii) $$\frac{\mu_{0} n i}{r}$$
(iii) $$\frac{2 \mu_{0} n i}{r}$$
(i) $$\frac{\mu_{0} n i}{2 r}$$