12th Physics Additional One Marks

12th Physics Additional One Marks from Previous Question Paper

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💡 12th Physics One Mark Short Cuts

One Marks From Previous Question Papers

1. In Fleming’s Right Hand Rule, the forefinger represents the direction of
a) motion of the conductor
b) magnetic field
c) induced current
d) none of the above

✅ Answer: b) magnetic field

2. The unit for Electric Flux is
a) C² N⁻¹ m⁻²
b) N m² C⁻²
c) N m² C⁻¹
d) N m⁻² C⁻¹

✅ Answer: c) N m² C⁻¹

3. The ratio of magnetic length and geometrical length is (Repeated Multiple Time)

a) 0.833
b) 0.633
c) 0.933
d) 0.733

✅ Answer: a) 0.833

4. For a healthy eye, the distance of the near point is ____

a) 30 cm
b) 20 cm
c) 35 cm
d) 25 cm

✅ Answer: d) 25 cm

5. The number of electrons in one coulomb of negative charge are (Repeated Multiple Times)

a) $6.25 \times 10^{-18}$ 6.25×10−18 electrons
b) $6.25 \times 10^{20}$ 6.25×1020 electrons
c) $6.25 \times 10^{25}$ 6.25×1025 electrons
d) $6.25 \times 10^{18}$ 6.25×1018 electrons

✅ Answer: d) $6.25 \times 10^{18}$ electrons

6. The radius of the 10th orbit of hydrogen atom is 52.9 Å. Calculate the de Broglie wavelength of the electron orbiting in the 10th orbit.

a) 16.64 Å
b) 3.322 Å
c) 33.22 Å
d) 6.64 Å

✅ Answer: c) 33.22 Å

7. Electromagnetic waves travel in a medium which has relative permeability 2.0 and relative permittivity 2.0. Then the speed of the electromagnetic wave in the medium will be

a) $3.6 \times 10^8$ m/s
b) $3 \times 10^8$ m/s
c) $1.5 \times 10^8$ m/s
d) $1.5 \times 10^2$ m/s

✅ Answer: c) 1.5×1081.5 \times 10^81.5×108 m/s

8. For the given logic circuit, the output will be 1 under which of the following conditions

a) A = 0, B = 0, C = 1, D = 0
b) A = 1, B = 0, C = 1, D = 0
c) A = 0, B = 1, C = 0, D = 1
d) A = 0, B = 1, C = 1, D = 1

✅ Answer: d) A = 0, B = 1, C = 1, D = 1

8. The average binding energy of iron nuclei is ____

a) 8.8 eV
b) 8.8 MeV
c) 8.5 eV
d) 8.5 MeV

✅ Answer: 8.8 MeV

9. The critical angle of diamond is ____

a) 37°
b) 31°
c) 49.8°
d) 24.4°

✅ Answer: 24.4°

10. The dielectric strength of air is ______

a) $1 \times 10^6$ Vm⁻¹
b) $6 \times 10^6$ Vm⁻¹
c) $3 \times 10^6$ Vm⁻¹
d) $9 \times 10^6$ Vm⁻¹

✅ Answer: c) $3 \times 10^6$ Vm⁻¹

11. The ratio of collector current to the base current is

a) Current gain in CE configuration
b) Current gain in CC configuration
c) Current gain in CB configuration
d) All of these

✅ Answer: Current gain in CE configuration

12. The circuit equivalent to

a) AND gate
b) OR gate
c) NOR gate
d) EXOR gate

✅ Answer: OR gate

13. In a Wheatstone’s bridge P=10Ω , Q=100Ω and R=40Ω. If the galvanometer shows zero deflection, the value of S is

a) 1000 Ω
b) 100 Ω
c) 40 Ω
d) 400 Ω

✅ Answer: 400 Ω

14. The equation for an alternating current is given by i=77sin⁡314ti = 77 \sin 314ti=77sin314t. Its frequency is

a) 50 Hz
b) 314 Hz
c) 77 Hz
d) 628 Hz

✅ Answer: 50 Hz

15. The magnitude of the magnetic field of a long, straight wire carrying a current of 1 A, at a distance of 1 m from it is

a) $2 \times 10^{-7}$ T
b) $2 \times 10^{7}$ T
c) $1 \times 10^{-7}$ T
d) $4 \times 10^{-7}$ T

✅ Answer: 2×10−7 T

16. The cut-off wavelength of X-rays from an X-ray tube of accelerating potential 20,000 V is

a) 1240 Å
b) 2.28 Å
c) 1.24 Å
d) 0.62 Å

✅ Answer: (d) 0.62 Å

17. In Hydrogen atom, the ground state ionization energy is

a) 13.6 eV
b) −13.6 eV
c) 10.2 eV
d) 12.1 eV

✅ Answer: (a) 13.6 eV

18.In the given diagram, a point charge +q is placed at the origin O. Work done in taking another point charge –Q from point A to point B is

a) $-\dfrac{qQ}{4\pi\varepsilon_0 a^2}\left(\dfrac{a}{\sqrt{2}}\right)$ −4πε0a2qQ(2a)
b) zero
c) $\left[-\dfrac{qQ}{4\pi\varepsilon_0 a^2}\right]\sqrt{2}a$ [−4πε0a2qQ]2a
d) $\left[\dfrac{qQ}{4\pi\varepsilon_0 a^2}\right]\sqrt{2}a$ [4πε0a2qQ]2a

✅ Answer: (b) zero

19. Two light waves from slit S1S_1S1 and S2S_2S2 on reaching points P and Q on a screen in Young’s double slit experiment have path difference zero and λ/4\lambda/4λ/4 respectively. The ratio of light intensities at P and Q will be

a) 4 : 1
b) 3 : 2
c) √2 : 1
d) 2 : 1

✅ Answer: (d) 2 : 1

20. Type of material which emits white light in LED

a) GaInN
b) SiC
c) AlGaP
d) GaAsP

✅ Answer: (a) GaInN

21. Charging current for a capacitor is 0.2 A, find the displacement current

a) zero
b) 0.2 A
c) 0.4 A
d) 0.1 A

✅ Answer: (b) 0.2 A

22. A charge qqq moves in a region where electric field and magnetic field both exist, then force on it is

a) $q(\vec{v} \times \vec{B})$
b) $q\vec{E} + q(\vec{B} \times \vec{v})$
c) $q\vec{E} + q(\vec{v} \times \vec{B})$
d) $q\vec{B} + q(\vec{E} \times \vec{v})$

✅ Answer: (c) $q\vec{E} + q(\vec{v} \times \vec{B})$

23. The direction of force on a current carrying conductor placed in a magnetic field is given by

a) Fleming’s Left Hand rule
b) Fleming’s Right Hand rule
c) End Rule
d) Right Hand palm Rule

✅ Answer: (a) Fleming’s Left Hand rule

24. In β decay

a) Atomic number decreases by 1
b) Mass number decreases by 1
c) Proton number remains the same
d) Neutron number decreases by 1

✅ Answer: (d) Neutron number decreases by 1

25. According to the laws of Boolean algebra, the expression A+ABA + ABA+AB is equal to

a) A
b) AB
c) B
d) A

✅ Answer: (a) A

26. A capacitor of capacitance 4 μF is connected to a battery of 10 V. What is the energy stored in the capacitor?

a) $2 \times 10^{-6}$
b) $2 \times 10^{-4}$
c) 200 J
d) 20 J

✅ Answer: (b) $2 \times 10^{-4}$

27. Unit of mobility is

a) m s⁻¹
b) Ω m
c) m² V⁻¹ s⁻¹
d) m⁻² √s

✅ Answer: (c) m² V⁻¹ s⁻¹

28. The resistance of an ideal ammeter

a) 1 Ω
b) Infinity
c) zero
d) none of these

✅ Answer: (c) zero

29. Two nuclei have mass numbers in the ratio 1 : 8. Then the ratio of their nuclear radii is

a) 1 : 8
b) 1 : 2
c) 2 : 1
d) 8 : 1

✅ Answer: (b) 1 : 2

30. The value of Bohr radius is

a) $53 \times 10^{-15}$ m
b) $0.53 \times 10^{-10}$ m
c) $53 \times 10^{-12}$ m
d) $5.3 \times 10^{0.15}$ m

✅ Answer: (b) $0.53 \times 10^{-10}$ m

31. The charge of cathode rays particle is

a) Positive
b) Negative
c) Neutral
d) Not defined

✅ Answer: (b) Negative

32. Two nuclei have mass numbers in the ratio 1 : 8. Then the ratio of their nuclear radii is

a) 1 : 8
b) 1 : 2
c) 2 : 1
d) 8 : 1

✅ Answer: (b) 1 : 2

33. If the angle of incidence is iii and the angle of reflection is rrr, then according to the law of reflection

a) $i = r$
b) $i > r$
c) $i < r$
d) All of these

✅ Answer: (a) i=r

35. The value of 1 eV is

a) $1.602 \times 10^{19}$
b) $1.602 \times 10^{-19}$ J
c) 1.602 J
d) $1.206 \times 10^{2}$ J

✅ Answer: (b) $1.602 \times 10^{-19}$ j

36. Non-polar molecule

a) H₂O
b) N₂O
c) HCl
d) CO₂

✅ Answer: (d) CO₂

37. The value of Gyro-magnetic ratio

a) $8.78 \times 10^{10}$ C kg⁻¹
b) $7.87 \times 10^{10}$ C kg⁻¹
c) $8.78 \times 10^{-10}$ C kg⁻¹
d) $1.6 \times 10^{-19}$ C kg⁻¹

✅ Answer: (a) $8.78 \times 10^{10}$ C kg⁻¹

38. A 400 mH coil of negligible resistance is connected to an AC circuit in which an effective current of 6 mA is flowing. The inductive reactance of the coil is

a) 240 Ω
b) 314 Ω
c) 125 Ω
d) 251 Ω

✅ Answer: (c) 125 Ω

39. According to quark model, number of up and down quarks in proton is

a) 2, 1
b) 1, 2
c) 3, 1
d) 1, 3

✅ Answer: (a) 2, 1

40. Which of the following is an example of polar molecule?

a) H₂O
b) CO₂
c) H₂
d) None of these

✅ Answer: (a) H₂O

41. Barkhausen condition for sustained oscillation is

a) $|A\beta| = 1$ ∣Aβ∣=1
b) $|A\beta| = 0$ ∣Aβ∣=0
c) $|A\beta| = -1$ ∣Aβ∣=−1
d) $|AB| = 1$ ∣AB∣=1

✅ Answer: (a) ∣Aβ∣=1|A\beta| = 1∣Aβ∣=1

42. The barrier potential of a silicon diode at 25°C is

a) 0.7 eV
b) 0.3 eV
c) 0.7 V
d) 0.3 V

✅ Answer: (c) 0.7 V

43. Two resistors of resistance values 4 Ω and 6 Ω are connected in series to a 24 V battery. Then the current in the circuit is

a) 24 A
b) 1 A
c) 10 A
d) 2.4 A

✅ Answer: (d) 2.4 A

44. If the Power is 2 MW, Resistance is 40 Ω and Voltage is 100 kV, then the power loss is

a) 16 MW
b) 1.6 MW
c) 0.16 MW
d) 0.016 MW

✅ Answer: (d) 0.016 MW

45. If an electron is accelerated through a potential difference of 10210^2102 V then its de Broglie wavelength is

a) 12.27 Å
b) 122.7 Å
c) 1.227 Å
d) 0.1227 Å

✅ Answer: (c) 1.227 Å

46. Which one of the following represents Power factor?

a) R/Z
b) Z/R
c) P/M
d) None

✅ Answer: (a) R/Z

47. The efficiency value for a half wave rectifier is

a) 4.6%
b) 81.2%
c) 40.6%
d) 8.12%

✅ Answer: (c) 40.6%

48. In a transistor connected in the common base configuration, α=0.95 and IE=1 . The value of IC is

a) 0.95 mA
b) 0.05 mA
c) 0.5 mA
d) 10.095 mA

✅ Answer: (a) 0.95 mA

49. 1λ=R(122−1n2)\frac{1}{\lambda} = R\left(\frac{1}{2^2} – \frac{1}{n^2}\right)λ1=R(221−n21) represents

a) Lyman Series
b) Paschen Series
c) Brackett Series
d) Balmer Series

✅ Answer: (d) Balmer Series

50. Isobars are examples of

a) Isotopes
b) Isobars
c) Isotones
d) Both Isotopes and Isobars

✅ Answer: (b) Isobars

51. If an electron is accelerated through a potential difference of 10 V, then its de Broglie wavelength is

a) 12.27 Å
b) 122.7 Å
c) 227 Å
d) 0.1227 Å

✅ Answer: (a) 12.27 Å

52. The Lens equation is

a) $\frac{1}{v} – \frac{1}{u} = \frac{1}{f}$
b) $\frac{f}{v} – \frac{1}{u} = \frac{1}{f}$
c) $\frac{1}{u} + \frac{1}{v} = \frac{1}{f}$
d) $u + v = \frac{1}{f}$

✅ Answer: (c) c) $\frac{1}{u} + \frac{1}{v} = \frac{1}{f}$ u1+v1=f1

53. If the refractive index n of the medium is sqrt 3, then the value of polarising angle is

a) 30°
b) 60°
c) 45°
d) 90°

✅ Answer: (b) 60°

Preparing for the Tamil Nadu 12th Physics Public Exam becomes easier when students practice questions from previous year question papers. In this section, you will find Additional One Mark Questions collected from previous board exams, revision tests, quarterly exams, and model question papers.

These questions are carefully selected based on the important concepts, repeated questions, and exam trends followed by the Tamil Nadu State Board. Practicing these extra one-mark questions will help students quickly revise key formulas, definitions, and concepts from every chapter.

This page is especially useful for students who want to score full marks in the one-mark section of the Physics exam. Go through these questions regularly and test your understanding to improve your confidence before the public examination.