#### 12th Standard English Medium Physics Reduced syllabus Creative one mark Question with Answerkey - 2021(Public Exam )

12th Standard

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Physics

Time : 01:00:00 Hrs
Total Marks : 50

Multiple Choice Questions(Creative)

50 x 1 = 50
1. The torque experienced by a rectangular current loop placed perpendicular to a uniform magnetic field is

(a)

maximum

(b)

minimum

(c)

finite minimum

(d)

zero

2. Lenz's law is in accordance with the law of

(a)

conservation of charges

(b)

conservation of flux

(c)

conservation of momentum

(d)

conservation of energy

3. The efficiency of an ideal transformer is

(a)

0

(b)

1

(c)

infinite

(d)

none

4. The average power consumed per cycle is:

(a)

Zero

(b)

2000 W

(c)

1000 W

(d)

500 W

5. An object is placed at 20 cm from a convex mirror of focal length 10 cm. The image formed by the mirror is

(a)

Real and 20 cm from the mirror

(b)

Virtual and at 20 cm from the mirror

(c)

Virtual and 20/3 cm from the mirror

(d)

Real and 20/3 cm from the mirror

6. Given a point source of light, which of the following can produce a parallel beam of light

(a)

Convex mirror

(b)

Concave mirror

(c)

Concave lens

(d)

Two plane mirrors inclined at an angle of 90°

7. A vehicle has a driving mirror of focal length 30 cm. Another vehicle of dimension 2 x 4 x 1.75 m3is 9 m away from the mirror of first vehicle. Position of the second vehicle as seen in the mirror of first vehicle is

(a)

30 cm

(b)

60 cm

(c)

90 cm

(d)

9 cm

8. If the radius of third Bohr orbit in hydrogen atom is r, then de-Broglie wavelength of electron in this orbit is

(a)

$\frac { r }{ 3 }$

(b)

3r

(c)

$\frac { 2\pi r }{ 3 }$

(d)

3(2πr)

9. The third electromagnet put in the path of an electron beam in an electron microscope is called _________

(a)

projector magnetic lens

(b)

accelerator

(c)

velocity selector

(d)

oscilloscope

10. If v = c, the mass of the moving body, of rest, mass 'mo' is _________

(a)

zero

(b)

infinity

(c)

m0

(d)

$\frac { m }{ { m }_{ 0 } }$

11. Find the accelerating potential of an electron whose de Broglie wave length is 3 Å

(a)

150.5 V

(b)

6.63 V

(c)

37.53 V

(d)

16.73 V

12. The de Broglie wavelength of electron accelerated with a potential V is ________

(a)

$\lambda =\frac { h }{ \sqrt { Vem } }$

(b)

$\lambda =\frac { h }{ \sqrt { 2Vem } }$

(c)

$\lambda =\frac { h }{ m\sqrt { 2Vem } }$

(d)

$\lambda =\frac { h }{ m\sqrt { \frac { Ve }{ m } } }$

13. When hydrogen atom is in its first excited level, its radius is __________ of the Bohr radius.

(a)

twice

(b)

same

(c)

half

(d)

four times

14. The ionisation potential of hydrogen atom is

(a)

13.6eV

(b)

-13.6eV

(c)

13.6 V

(d)

-13.6 V

15. The velocity of cathode rays is upto ________ the velocity of light.

(a)

0.10

(b)

0.001

(c)

10.5

(d)

0.01

16. The charge of an alpha-particle is _______________

(a)

same as that of a proton

(b)

twice as that of an electron

(c)

thrice as that of an proton

(d)

twice as that of a neutron

17. The orbits in which electrons supposed to be revolving according to Rutherford are ___________

(a)

square-shaped

(b)

circular

(c)

rectangular

(d)

linear

18. The value of Bohr radius is __________ m.

(a)

53 x 10-15

(b)

0.53 x 10-12

(c)

53 X 10-12

(d)

53 x 10-15

19. When the electron jumps from any of the outer orbits to the first orbit, spectral lines are emitted in the ________ region.

(a)

visible

(b)

IR

(c)

X-ray

(d)

UV

20. If in a hydrogen spectrum, n1 = 2 and n2 = 3, 4, 5... then the series is called ___________ series.

(a)

Lyman

(b)

Balmer

(c)

Brackett

(d)

Pfund

21. Paschen series of hydrogen atom comes under ___________ region.

(a)

IR

(b)

UV

(c)

X-ray

(d)

Gamma ray

22. Energy of an atom at its ground state is ___________

(a)

zero

(b)

maximum

(c)

minimum

(d)

10 eV

23. The process of giving extra energy to an electron in an orbit is called ________ of the atom

(a)

grounding

(b)

excitation

(c)

sinking

(d)

induction

24. Which particle cannot be emitted by radioactive element during their decay?

(a)

neutrino

(b)

helium nuclei

(c)

photons

(d)

electrons

25. In gamma ray emission from nucle

(a)

both the neutron number and the proton number change

(b)

there is no change in neutron number and the proton number change

(c)

only the neutron number changes

(d)

only the proton number changes

26. Gamma rays are extensively used to destroy __________ affected cells

(a)

Sickle-cell anaemia

(b)

Cancer

(c)

HIV

(d)

Polio virus

27. In the nuclear reaction 4Be9+ X ➝ 6C12+ 0n1 X stands for

(a)

proton

(b)

α particle

(c)

electron

(d)

deutron

28. Roentgen (R) is the unit to measure _________

(a)

X-ray strength

(b)

number of holes produced by X-rays

(c)

(d)

number of cancer cells

29. To convert fertile material into fissile material, we make use of _______ reactors.

(a)

research

(b)

production

(c)

power

(d)

generator

30. _______ is synthesized top down approach

(a)

Ball milling

(b)

Plasma etching

(c)

lithography

(d)

Ball milling and lithography

31. Which statement is incorrect regarding for p-n junction.

(a)

Donor atoms are depleted of their holes in junction

(b)

No net charge exists far from junction

(c)

Barrier potential VB is generated

(d)

Energy VB is to be surmounted before any charge can flow across junction

32. In a N-P-N transistor circuit, the emitter, collector and base current are respectively IE, IC and lB. The relation between them is

(a)

ICEB

(b)

IBCE

(c)

IB>IC>IE

(d)

IB>IC>IE

33. In an P.N.P transistor circuit, the collector current is 10 mA. If 90% of the electrons emitted reach the collector

(a)

IE=9mA

(b)

IE=10mA

(c)

IB= 1mA

(d)

IB= - 1mA

34. Which of the following figure represents an ideal diode characteristics?

(a)

(b)

(c)

(d)

35. For Boolean identities match the pair
1. $\overset { = }{ A }$ (P) Ā + $\bar { B }$
2. $\overline { A+B }$ (Q) A.B
3. $\overline { A.B }$ (R) $\bar { A } .\bar { B }$
4. A.(Ā + B) (S) A

(a)

1 - (S), 2 (P), 3 - (Q), 4 - (R)

(b)

1 - (S), 2 (R), 3 - (Q), 4 - (P)

(c)

1 - (S), 2 (Q), 3 - (P), 4 - (R)

(d)

1- (S), 2 (R), 3 - (P), 4 - (Q)

36. The process of increasing the strength of a signal using an electric circuit is called

(a)

amplification

(b)

modulation

(c)

demodulation

(d)

transmission

37. Ground wave have wavelength

(a)

less than that of sky waves

(b)

greater than that of sky wave

(c)

less than that of space waves

(d)

equal to that of space waves

38. When NPN transistor is used as an amplifier then _____________

(a)

'electron moves from base to collector

(b)

hole travels from emitter to base

(c)

hole goes to emitter from base

(d)

electron goes to base from collector

39. In space communication, the sound waves can be sent from one place to another

(a)

through space

(b)

through wires

(c)

by super imposing it on undamped EM waves

(d)

by super imposing it on damped EM waves

40. Doping of a semiconductor generally changes resistivity as follows

(a)

increases

(b)

decreases

(c)

does not alter

(d)

may increase

41. Skip distance the shortest distance between

(a)

the point of transmission and the point of reception

(b)

(c)

the transmitter and the target

(d)

42. The process.of superimposing the audio signal over the carrier wave is called ________

(a)

superposition

(b)

modulation

(c)

demodulation

(d)

extraction

43. The radiation of electrical energy is practicable only above _________

(a)

20 kHz

(b)

200 MHz

(c)

200 kHz

(d)

20 Hz

44. Reverse bias applied to a junction diode

(a)

increases the potential barrier

(b)

increases the majority carrier current

(c)

lowers the potential barrier

(d)

increases the minority carrier current

45. If the distance between the conduction band and valence band is leV, then this combination is

(a)

semiconductor

(b)

metal

(c)

insulator

(d)

conductor

46. The total variation in frequency of a FM transmitter is called _______

(a)

signal swing

(b)

carrier swing

(c)

shift

(d)

difference

47. In a transmitter, the _______ isolates the RF amplifier from the oscillator.

(a)

amplifier

(b)

oscillator

(c)

buffer

(d)

transistor

48. The ability to select a particular wanted signal only and rejecting the unwanted signals is called __________.

(a)

sensitivity

(b)

buffer action

(c)

reception

(d)

selectivity

49. Vacant energy levels are called _________

(a)

valence level

(b)

core level

(c)

conduction levels

(d)

compound level

50. The speaker converts ________ energy into ______ energy.

(a)

electrical, sound

(b)

sound, electrical

(c)

light, sound

(d)

sound, mechanica