12th Physics Chapter 4 Important Questions
12 ஆம் வகுப்பு இயற்பியல் பாடம் வாரியான முக்கியமான வினாக்கள்
12th Physics Chapter Wise Important Questions
12th Physics board exams, focusing on chapter-wise important questions is a strategic way to ensure high marks. Key areas include Electrostatics (Coulomb’s law and Gauss theorem), Current Electricity (Kirchhoff’s laws and Wheatstone bridge), and Electromagnetic Induction (Transformer and AC generator). In the latter half of the syllabus, Optics (lens maker’s formula) and Modern Physics (half-life and nuclear reactors) are essential for 5-mark sections. Mastering these high-weightage topics, along with practicing previous year question papers and numerical problems, helps students build conceptual clarity and time management skills for the final exam.
12-ஆம் வகுப்பு இயற்பியல்: முக்கிய வினாக்கள். 12-ஆம் வகுப்பு இயற்பியல் தேர்வில் அதிக மதிப்பெண்கள் (Centum) பெற, மாணவர்கள் பாடவாரியாக உள்ள முக்கியமான வினாக்களில் அதிக கவனம் செலுத்த வேண்டும்.
12th Physics Important Questions – CHAPTER 4
12th Physics Chapter 4 Important – 2 Marks
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1. State Faraday‟s laws of electromagnetic induction.
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2. State Lenz‟s law. (SEP 20, JUNE 23,MAR 25)
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3. State Fleming‟s right hand rule. (MAY 22)
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4. Mention the ways of producing induced emf. (AUG 21,JULY 22,JUNE 24)
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5. What do you mean by self-induction?
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6. What is meant by mutual induction?
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7. What are step-up and step-down transformers?
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8. Define average value of an alternating current.
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9. How will you define RMS value of an alternating current?
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10. Define electric resonance.
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11. How will you define Q-factor? (MAR 23)
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12. What is meant by wattles current?
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13. Give any one definition of power factor.
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14. An ideal transformer has 460 and 40,000 turns in the primary and secondary coils respectively. Find the voltage developed per turn of the secondary if the transformer is connected to 230V AC mains. (Example 4.16) (MAR 20)
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15. A straight metal wire crosses a magnetic field of flux 4mWb in a time 0.4s. Find the magnitude of the emf induced in the wire. (Ex:2, CH-4) (MAR 24)
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16. Calculate the instantaneous value at 60o , average value and RMS value of an alternating current whose peak value is 20 A. (Ex: 20, CH-4)
12th Physics Chapter 4 Important – 3 Marks
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1. Obtain an expression for motional e m f from Lorentz force.
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2. Assuming that the length of the solenoid is large when compared to its diameter, find the equation for its inductance. (MAR 24)
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3. An inductor of inductance L carries an electric current i. How much energy is stored while establishing the current in it?
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4. How will you induce an emf by changing the area enclosed by the coil? (MAR 23,25)
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5. Explain the construction and working of transformer.
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6. Mention the various energy losses in a transformer. (JUNE 23, AUG 21)
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7. Prove that the total energy is conserved during LC oscillations.
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8. Explain AC containing pure resistor.
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9. What are the advantages and disadvantages of AC system over DC system? (JULY 22, MAR 20,25)
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10. Obtain an expression for average power of AC over a cycle.
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11. Find the impedance of a series RLC circuit if the inductive reactance, capacitive reactance and resistance are 184Ω, 144Ω and 30Ω respectively. Also calculate the phase angle between voltage and current. (Exam- 4.22) (MAY 22)
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12. A 500𝜇𝐻 inductor, 80𝑝𝐹 capacitor and a 628𝛺 resistor are connected to form a series RLC circuit. Calculate the resonant frequency and Q-factor of this circuit at resonance. (Exam- 4.23) (SEP 20)
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13. A coil of 200 turns carries a current of 4A. If the magnetic flux through the coil is 6×10–5Wb, find the magnetic energy stored in the medium surrounding the coil. (Ex-10, CH-4) (JUNE 24)
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14. A circular metal of area 0.03 m2 rotates in a uniform magnetic field of 0.4 T. The axis of rotation passes through the centre and perpendicular to its plane and is also parallel to the field. If the disc completes 20 revolutions in one second and the resistance of the disc is 4 Ω, calculate the induced emf between the axis and the rim and induced current flowing in the disc. (Exam 4.14) (MAR 25)
12th Physics Chapter 4 Important – 5 Marks
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1. Show that the mutual inductance between a pair of coils is same (M12=M21). (JULY 22)
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2. Show mathematically that the rotation of a coil in a magnetic field over one rotation induces an alternating emf of one cycle. (MAR 20, JUNE 24)
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3. Explain the working of a single-phase AC generator with necessary diagram. (JUNE 23)
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4. Explain the construction and workings of transformer and define its efficiency. (SEP 20, MAY 22)
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5. Find out the phase relationship between voltage and current in a pure inductive circuit. (MAR 20,24)
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6. Derive an expression for phase angle between the applied voltage and current in a series RLC circuit.(AUG 21, MAR 23)
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7. Find out the phase relationship between voltage and current in a pure capacitor.
