PUNJAB NEWS ONLINE: PHYSICS SOLVED QUESTION PAPER IMPORTANT DOR PSEB/ CBSE

Time 1.5 hr Class XII

Sub Physics MM 35 September 2021

NOTE: 1. Question paper has 35 multiple choice questions.

2. Each question is compulsory.

3. Q.1 to 11 are knowledge based questions, Q.12 to 24 are understanding based questions & Q.25 to 35 are application based questions.

Q1 The angle between the electric dipole moment (`P⃗` ) and electric field (`E⃗` ) due to the dipole at a point on its axial and equatorial lines respectively are

a) `0^{0}` , `180^{0}`
b) `90^{0}` , `180^{0}`
c) `180^{0}` , `0^{0}`
d) `0^{0}` , `90^{0}`

a) `0^{0}` , `180^{0}`

Q2 Unit of capacity of conductor is farad. 1 farad(F) is equal to

(a)1F = `\frac{1 coloumb}{1ampere}`
(b) 1F = `\frac{1 ampere }{1 coloumb}`
(c) 1F = `\frac{1 coloumb}{1 vol.t}`
(d) 1F = `\frac{1 vol.t}{1 coloumb}`

Q3 The material of wire of potentiometer is :

(a) Copper, because it has high conductivity
(b) Steel, because it is very hard and rust free.
(c) Manganin, because of high resistivity and low temperature coefficient of resistivity.
(d) Aluminium, because it is a good conductor and cheaper than copper

Q4 A cyclotron cannot be used to accelerate the electrons because

(a) Electrons are very heavy and they cannot rotate with the frequency of oscillating electric field.
(b) Electrons are negative charged particles. Therefore, they do not get accelerated inside an electric field.
(c) Electrons are very light particles, they are accelerated at once. They go out of step with oscillating electric field and hence cannot be accelerated.
(d) Electrons mass changes into energy by Einstein formula E = mc2 and therefore they disappear from the system.

(c) Electrons are very light particles, they are accelerated at once. They go out of step with oscillating electric field and hence cannot be accelerated.

Q5 The angle of dip at the magnetic equator and magnetic poles respectively is

a) `0^{0}` , `45^{0}`
b) `45^{0}` , `45^{0}`
c) `90^{0}` , `0^{0}`
d) `0^{0}` , `90^{0}`

d) `0^{0}` , `90^{0}`

Q6 Two long parallel wires carrying equal amount of currents in same directions and placed 1m away attract each other with a force of 2 × `10^{-7}` N per meter of their lengths, then current in each wire will be:

(a) 0 A
(b) 1A
(c) 2A
(d) 3A

(b) 1A

Q7 The magnetic lines of force around an infinitely long straight current carrying conductor are

(a) Concentric circles around conductor
(b) Parallel to length of conductor
(c) Perpendicular to length of conductor
(d) None of these

(a) Concentric circles around conductor

Q8 A metal rod of length 'l' moves with velocity 'v' along the direction of uniform magnetic field `B⃗` , then the motional EMF developed across the ends of the rod is equal to

(a) e = B𝑙v
(b) e = 0
(c) e = B𝑙/v
(d) e = Bv/l

(a) e = B𝑙v

Q9. Eddy current may be reduced by using:

(a) thick piece of plastic
(b) laminated core of soft iron
(c) thick piece of cobalt
(d) thick piece of nickel

(b) laminated core of soft iron

Q10 . Effective resistance of an electric circuit to alternating current, arising from combined effect of ohmic resistance and reactance is called:

(a) Capacitance
(b) Tolerance
(c) Impedance
(d) Inductance

Q11 Which of the following radiations are used respectively for Lasik eye surgery and to take photograph during the conditions of fog and smoke?

(a) Visible rays, X rays
(b) Ultraviolet rays, Infrared rays
(c) Infrared Rays, Ultraviolet rays
(d) Microwaves, Gamma rays

(b) Ultraviolet rays, Infrared rays

Q12 The equipotential surfaces produced by single positive or negative charge are concentric spheres. The gap between these spheres as we move away from charge

(a) decreases
(b) remains same
(c) increases
(d) first increases and then decreases

Q13 If a wire of resistance R and resistivity ρ is stretched to double its length, then its new resistance and resistivity will become

(a) 4R, ρ/2
(b) 4R, 4 ρ
(c) 4R, ρ
(d) R/4, 2ρ

c) 4R, ρ

Q14 The sensitivity of a potentiometer can be increased by

(a) Increasing length of wire and decreasing resistance in series with the potentiometer wire
(b) Decreasing length of wire and decreasing resistance in series with the potentiometer wire
(c) Increasing length of wire and increasing resistance in series with the potentiometer wire
(d) Decreasing length of wire and increasing resistance in series with the potentiometer wire

Q15 . A compass needle does not work at magnetic poles because

(a) Compass needle is free to move in a vertical plane only
(b) Compass needle is free to move in a horizontal plane only
(c) Compass needle cannot measure earth magnetic field because it is very weak.
(d) Weight of compass needle becomes more at poles.

(b) Compass needle is free to move in a horizontal plane only

Q16 The resistance of voltmeter, ammeter and galvanometer in the increasing order can be written as

(a) Rvoltmeter < Rammeter < Rgalvanometer
(b) Rammeter < Rvoltmeter < Rgalvanometer
(c) Rvoltmeter < Rgalvanometer < Rammeter
(d) Rammeter < Rgalvanometer < Rvoltmeter

(d) Rammeter < Rgalvanometer < Rvoltmeter

Q17 The earth’s core has iron but it is not regarded as source of earth’s magnetism because:

(a) Iron does not show magnetic properties
(b) Temperature of earth’s core is very high and at this temperature iron does not remain ferromagnetic.
(c) Iron is a superconducting material
(d) None of these

(b) Temperature of earth’s core is very high and at this temperature iron does not remain ferromagnetic.

Q18 Magnetic field due to a current carrying conductor is zero:

(a) along a line perpendicular to the wire
(b) along the axial line of the wire
(c) along a line inclined 45° to the wire
(d) it can never be zero

(b) along the axial line of the wire

Q19. A lamp is connected in series with a capacitor to a high frequency AC source. Then it is connected directly to the same source which is true statement about this.

(a) Lamp will glow more brightly when the capacitor is in series with it.
(b) Lamp will glow more brightly on connecting it directly to the source.
(c) Lamp glows with same brightness in both cases.
(d) Brightness of glow of bulb does not depend upon capacitive reactance.

(b) Lamp will glow more brightly on connecting it directly to the source.

Q20 . The current in series LCR circuit will be maximum when angular frequency ω is

(a) as large as possible
(b) equal to natural frequency of LCR circuit
(c) `(LC)^{1/2}`
(d) 1/LC

(b) equal to natural frequency of LCR circuit

Q21 The current flowing from A to B is increasing as shown in the figure. The direction of the induced current in the loop is

(a) clockwise
(b) anticlockwise
(c) straight line
(d) no induced e.m.f. produced

(a) clockwise

Q22 Gamma rays are used in radiation therapy in order to treat cancer because

(a) Gamma rays have magical therapeutic properties.
(b) Gamma rays travel faster then other electromagnetic radiations.
(c) Gamma rays are highly energetic and can destroy cancer cells.
(d) None of these

Q23 The equation of electric field part of an electromagnetic wave is given by 𝐄⃗ = [ 3.1 cos { 1.8 y + 5.4 × `10^{6}` t } ] i(unit vector i) , the directions of oscillation of electric field, magnetic field and propagation of wave respectively are

(a) x axis, y axis, +z axis
(b) z axis, y axis, +x axis
(c) x axis, z axis, +y axis
(d) x axis, z axis, −y axis

(d) x axis, z axis, −y axis

Q24 The electromagnetic spectrum in the increasing order of frequency is given as Radio waves, microwaves, Infrared rays, visible rays, Ultraviolet rays, X-rays, Gamma rays. Which physical quantity is same for all these waves in vacuum?

(a) wavelength
(b) speed
(c) energy
(d) all of these

(b) speed

Q25 What capacitance is required to store an energy of 100 KWh at a potential difference of `10^{4}` V?

a) 9.2 F
b) 3.7 F
c) 7.2 F
d) 2.7F

c) 7.2 F

Q26 Two similar capacitors of capacity C each are first connected in series and then in parallel. The ratio of the net capacity obtained in the two cases is

(a) 4
(b) 1/4
(c) 1
(d) 2

(b) 1/4

Q27 The resistances of two bulbs at the same voltage are in the ratio 1:2. On connecting them in parallel, the power consumption will be in the ratio

(a) 2:1
(b) 1:1
(c) 1:4
(d) 1:2

(a) 2:1

Q28 A Galvanometer of resistance 12 ohm gives full deflection for 8 mA. It can be converted into voltmeter of range 0-32 V with help of resistance of:

(a) 5988 ohm
(b) 3988 ohm
(c) 2500 ohm
(d) 4000 ohm

(b) 3988 ohm

Q29. In the magnetic meridian of a certain place, the horizontal component of earth’s magnetic field is 0.26 G and the dip angle is `60^{0}` , the vertical component of earth’s magnetic field at that place will be (G → gauss)

(a) `\frac{0.26}{\sqrt{3}}`G
(b) `\sqrt{3}`G
(c) 0.52 G
(d) 0.13 G

(b) `\sqrt{3}`G

Q30 . Magnetic susceptibility of magnesium at 300K of temperature is 1.2 × `10^{-5}` , the magnetic susceptibility of magnesium at 30K of temperature will be

(a) 1.2 × `10^{-3}`
(b) 1.2 × `10^{-4}`
(c) 1.2 × `10^{-5}`
(d) 1.2 × `10^{-6}`

(b) 1.2 × `10^{-4}`

Q31 The smallest value of magnetic dipole moment 𝝁l of an atom due to orbital motion of an electron in first orbit is called Bohr Magneton 𝜇B. The value of Bohr Magneton is equal to

a) 𝝁B=9.27x `10^{-24}`A`m^{2}`
b) 𝝁B=1.38x `10^{-23}`A`m^{2}`
c) 𝝁B=6.022x `10^{23}`A`m^{2}`
d) 𝝁B=1.6x `10^{-19}`A`m^{2}`

a) 𝝁B=9.27x `10^{-24}`A`m^{2}

Q32 The magnetic flux passing through a coil changes from 6×`10^{-3}` Wb to 7.2×`10^{-3}` Wb in 0.02s.Calculate the induced e.m.f.:

(a) -6×`10^{-2}`V
(b) 8×`10^{-2}`V
(c) 2×`10^{-2}`V
(d) -3×`10^{-2}`V

(a) -6×`10^{-2}`V

Q33 How much current is drawn by the primary coil of a transformer connected to 220V supply, when it delivers power to a 110V and 550 W refrigerator?

(a) 0.5 A
(b) 2.5 A
(c) 5 A
(d) 1.5 A

(b) 2.5 A

Q34 An inductor of 1 H and negligible resistance is used on the mains of frequency 50 Hz. Find the reactance of the inductor

(a) 50 π H
(b) 100 π H
(c) 75 π H
(d) 60 π H

(b) 100 π H

Q35 Find the wavelength of electromagnetic waves of frequency 6×`10^{12}` Hz in free space having speed of 3 × `10^{8}` m/s in free space

a) 6 x `10^{-5}`
b) 5 x `10^{-5}`
c) 2.5 x `10^{-5}`
d) 1.5 x `10^{-5}`

b) 5 x `10^{-5}`

JOBS OF TODAY

Labels

PHYSICS SOLVED QUESTION PAPER IMPORTANT DOR PSEB/ CBSE