10, 12ஆம் வகுப்பு மாணவர்களுக்கான பொதுத் தேர்வு மாதிரி வினாத்தாள்களை, ABP Nadu ஊடகம் ஆண்டுதோறும் வெளியிட்டு வருகிறது. அந்த வகையில்,12ஆம் வகுப்பு பாடங்களுக்கான மாதிரி வினாத்தாள்களை தினந்தோறும் வெளியிட்டு வருகிறோம்.


12ஆம் வகுப்பு இயற்பியல் பாடத்துக்கான மாதிரி வினாத்தாள் இதோ!


12- PHYSICS TIMING 3 HOURS TOTAL 70


Part – A


Choose the best option 10x1=10



  1. An electric dipole is placed at an alignment angle of 30” with an electric field of 2 x 105 NC - 1 . It experiences a torque equal to 8 Nm. The charge on the dipole if the dipole length is 1 cm is a) 4mc b) 8mC c) 5mC d) 7m Ans: b

  2. The internal resistance of 2.1 volt cell which gives a current of 0.2A through resistance of10 Ω (a) 0.2 Ω (b) 0.5 Ω (c) 0.8 Ω (d) 1.0 Ω Ans: b

  3. A circular coil of radius 5 cm and 50 turns carries a current of 3 ampere. The magnetic dipole moment of the coil is nearly a) 1.0Am² (b) 1.2Am² (c) 0.5Am² (d) 0.8 m² Ans: b

  4. In an oscillating LC circuit the maximum charge on the capacitor is Q. The charge on the capacitor when the energy stored equally between the electric and magnetic field is


(a)Q/2 (b)Q/√3 (c) Q/√2 (d)Q Ans: c



  1. Which of the following is used for viewing objects through fog

  2. a) microwave b)gamma rays c)X rays d)Infra red Ans: d

  3. For light instant from air on a slab of refractive index 2 , the maximum possible angle of refraction is (a) 30° (b) 45°(c) 60° (d) 90° Ans: a

  4. Light transmitted by Nicol Prism is a) partially polarised b) unpolarised c) plain polarized d) elliptically polarized Ans: c

  5. Emission of electrons by the absorption of heat energy is called _________ emission a) photoelectric b) field c) thermionic d) secondary Ans: c

  6. The ratio between the radius of first three orbits of hydrogen atom is a) 1:2:3 (b) 2:4:6 (C) 1:4:9 (d)1:3:5 Ans: c


 



  1. The zener diode is primary used as a) rectifier b) amplifier c) oscillator d)voltage regulator Ans: d

  2. The alloys is used for muscle wires in robots are a) shape memory alloys b) gold copper alloysc) gold silver alloys d) two dimensional alloys Ans: a

  3. Electric field inside the closed system is a) Positive b) negative c) same d) zero Ans: d

  4. Toaster operating A 240 V has a resistance of 120Ω. Its power is (a) 400 W (b)2 W (c)480 W (d) 240 W Ans: c

  5. A ray of light travelling in a transparent medium of refractive index n falls on surface separating the medium from air at an angle of incidents of 45°. The ray can undergo total internal reflection for the following n, (a) n=1.25 (b) n=1.33 (c) n=1.4 (d) n=1.5 Ans: c

  6. The charge of cathode rays particle is a) positive b) negative c) neutral d) not defined Ans: b


 


PART B II. Answer any 6 questions question number 24 is compulsory 6X2=12



  1. Define capacitance. Give its unit. The capacitance of a capacitor is defined as the ratio of the magnitude of charge (Q) on either of the conductor plates to the potential difference (V) existing between the conductors. (i.e) C = Q/V. Its unit is farad (F) or C V-1

  2. State Ampere’s circuital law. It state that the line integral of magnetic field over a closed loop is 𝝁𝒐 times net current enclosed by the loop. ∮ B . 𝒅𝒍 = 𝝁𝒐 𝑰𝒐

  3. Define Q factor. Q – factor is defined as the ratio of voltage across L or C to the applied voltage at resonance .

  4. What are Fraunhofer lines how are they useful in the identification of element present in the sun. When the spectrum obtained from the Sun is examined, it consists of large number of dark lines (line absorbtion spectrum). These dark lines in the solar spectrum are known as Fraunhofer lines. The absorption spectra for various materials are compared with the Fraunhofer lines in the solar spectrum, which helps to identifying elements present in the Sun’s atmosphere.

  5. What is the reason for reddish appearance of Sky during sunset and sunrise?


During sunset or sunrise, the light from Sun travels a greater distance through atmosphere. Hence the blue light which has shorter wavelength is scattered away and less scattered red light of longer wavelength reaches observer. This is the reason for reddish appearance of sky and Sun during sunrise and sunset


21.Give the relation between phase difference and Path difference. In the path of the wave, one wavelength corresponds to a phase of 2𝝅. Hence the path difference 𝛿 corresponds to a Phase difference 𝜙 is 𝜹 =(𝝀/𝟐 𝝅) 𝝓



  1. Define stopping potential. The negative or retarding potential given to collecting electrode which is just sufficient to stop the most energetic photoelectrons emitted and make the photo current zero is called stopping potential or cut – off potential.

  2. Define curie. One curie was defined as number of decays per second in 1 g of radium 𝟏 𝑪𝒊 = 𝟑. 𝟕 𝑿 𝟏𝟎𝟏𝟎 𝒅𝒆𝒄𝒂𝒚/𝒔𝒆𝒄𝒐𝒏𝒅

  3. Calculate the number of nuclei of carbon 14 undecayed after 22.920 years if the initial number of carbon 14 atom is 10.000. The time interval in terms of half-life, n = 1 𝑇1/2 = 22.920 5730 =4 The number of nuclei remaining undecayed after 22.920 years is, N=( 1 2 ) 𝑛 N0=( 1 2 ) 4 X10000=625 III. Answer any 6 questions question number 33 is compulsory. 6X3=18


 



  1. State Fleming’s right and rule. The thumb, index finger and middle finger of right hand are stretched out in mutually perpendicular directions. If index finger points the direction of magnetic field and the thumb points the direction of motion of the conductor, then the middle finger will indicate the direction of the induced current. Flemming’s right hand rule is also known as generator rule. 28. List out any six characteristics of photons. Characteristics of phoconserve 1.Each photon will have energy given by 𝑬 = 𝒉 𝝂 =𝒉 𝒄/𝝀 2.The energy of a photon is determined by the frequency of the radiation and not by its intensity. 3.The photons travel with the velocity of light and its momentum is given by, 𝒑 =𝒉/𝝀 = 𝒉 𝝂/𝒄 4. Photons are electrically neutral, and hence they are not deflected by electric and magnetic fields.


5.When photon interacts with matter, the total energy, total linear momentum and angular momentum are conserved. 29. Discuss the conversion of galvanometer into an ammeter