Haryana Bseh Class 12 Physics — Real Previous-Year Papers

For mass defect of 0.4% the binding energy of 1 kilogram material is: (a) 3.6 × 10¹4 ergs (b) 3.6 × 10^-14 J (c) 3.6 × 10^-14 ergs (d) 3.6 × 10¹4 J

Minority charge carriers in p-type material is: (a) Holes (b) Electrons (c) Both electrons and holes (d) None of these

Fill in the blank: The reciprocal of resistivity is .............

Fill in the blank: If coil is viewed from one end and the current flows in clockwise direction, then this end is a ............... pole.

Fill in the blank: The quantity measured across a cell without drawing any current from it, is ..... .

Answer in one word/sentence: If red light source is used instead of blue light in Young's double slit experiment, what happens with Fringe width?

Answer in one word/sentence: What is the phenomena that causes a bubble in water to shine brightly?

Answer in one word/sentence: What is the controlled addition of impurities to intrinsic semiconductor is called?

Assertion (A): The magnifying power of a simple microscope is inversely proportional to the focal length of the lens. Reason (R): Power of a lens is inversely proportional to the focal length. (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A). (b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). (c) Assertion (A) is true, but Reason (R) is false. (d) Assertion (A) and Reason (R) both are false.

Assertion (A): The momentum of photon is p = h/λ. Reason (R): A photon act as a massless particle. (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A). (b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). (c) Assertion (A) is true, but Reason (R) is false. (d) Assertion (A) and Reason (R) both are false.

Assertion (A): The force of repulsion between atomic nucleus and alpha particle varies with distance according to inverse square law. Reason (R): Rutherford did alpha scattering experiment. (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A). (b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A). (c) Assertion (A) is true, but Reason (R) is false. (d) Assertion (A) and Reason (R) both are false.

Case study: When a glass rod is rubbed with silk, the rod acquires one type of charge, and the silk acquires the other type of charge. This is true for any pair of objects that are rubbed with each other to be electrified. Now the electrified glass rod is brought in contact with silk cloth, which was rubbed; they no longer attract each other. They also do not repel or attract each other light pieces of paper and other such objects; thus, charges they acquire by rubbing get lost when they come in contact with each other. When you comb in dry hairs it gets charged due to? (a) Friction (b) Conduction (c) Induction (d) Grounding

Case study: When a glass rod is rubbed with silk, the rod acquires one type of charge, and the silk acquires the other type of charge. This is true for any pair of objects that are rubbed with each other to be electrified. Now the electrified glass rod is brought in contact with silk cloth, which was rubbed; they no longer attract each other. They also do not repel or attract each other light pieces of paper and other such objects; thus, charges they acquire by rubbing get lost when they come in contact with each other. Which part of atom physically manipulated in this type of electrification? (a) Protons (b) Electrons (c) Nucleus (d) Neutrons

Case study: When a glass rod is rubbed with silk, the rod acquires one type of charge, and the silk acquires the other type of charge. This is true for any pair of objects that are rubbed with each other to be electrified. Now the electrified glass rod is brought in contact with silk cloth, which was rubbed; they no longer attract each other. They also do not repel or attract each other light pieces of paper and other such objects; thus, charges they acquire by rubbing get lost when they come in contact with each other. Positive and negative charge on neutral objects are: (a) Double (b) Equal (c) Half (d) Four times

Case study: When a glass rod is rubbed with silk, the rod acquires one type of charge, and the silk acquires the other type of charge. This is true for any pair of objects that are rubbed with each other to be electrified. Now the electrified glass rod is brought in contact with silk cloth, which was rubbed; they no longer attract each other. They also do not repel or attract each other light pieces of paper and other such objects; thus, charges they acquire by rubbing get lost when they come in contact with each other. 3 balls K, L M have charged 1 C, 3 C and 4 C respectively. The ball K is first brought into contact with L and then M. Find the final charge on M. **OR** Why we observe electric shock on touching a metallic door handle after moving on the floor with carpet?

Case study: Bohr's model addressed the instability of the Rutherford model by introducing quantization. The model is based on three postulates, which successfully explained the discrete line spectrum of hydrogen. According to the model, the radius of the nth stationary orbit is rₙ ∝ n², and the total energy is Eₙ = −13.6 eV / n², when an electron jumps from a higher energy level (Eᵢ) to a lower one (Ef), a photon of energy hν = Eᵢ − Ef is emitted. Transitions ending at the n = 1 level form the Lyman series. According to Bohr's second postulate, which quantity is quantized? (a) Energy of electron (b) Orbital angular momentum (c) Linear momentum (d) Frequency of revolution

Case study: Bohr's model addressed the instability of the Rutherford model by introducing quantization. The model is based on three postulates, which successfully explained the discrete line spectrum of hydrogen. According to the model, the radius of the nth stationary orbit is rₙ ∝ n², and the total energy is Eₙ = −13.6 eV / n², when an electron jumps from a higher energy level (Eᵢ) to a lower one (Ef), a photon of energy hν = Eᵢ − Ef is emitted. Transitions ending at the n = 1 level form the Lyman series. The energy of an electron in the first excited state (n = 2) of hydrogen is: (a) –13.6 eV (b) –6.8 eV (c) –3.4 eV (d) –1.7 eV

Case study: Bohr's model addressed the instability of the Rutherford model by introducing quantization. The model is based on three postulates, which successfully explained the discrete line spectrum of hydrogen. According to the model, the radius of the nth stationary orbit is rₙ ∝ n², and the total energy is Eₙ = −13.6 eV / n², when an electron jumps from a higher energy level (Eᵢ) to a lower one (Ef), a photon of energy hν = Eᵢ − Ef is emitted. Transitions ending at the n = 1 level form the Lyman series. Transitions ending at n = 3 belong to which series? (a) Lyman series (b) Balmer series (c) Paschen series (d) Brackett series

Case study: Bohr's model addressed the instability of the Rutherford model by introducing quantization. The model is based on three postulates, which successfully explained the discrete line spectrum of hydrogen. According to the model, the radius of the nth stationary orbit is rₙ ∝ n², and the total energy is Eₙ = −13.6 eV / n², when an electron jumps from a higher energy level (Eᵢ) to a lower one (Ef), a photon of energy hν = Eᵢ − Ef is emitted. Transitions ending at the n = 1 level form the Lyman series. Explain the physical significance of the negative sign in the expression for the total energy Eₙ of an electron in the Bohr model. **OR** What is the ratio of the radius of the third Bohr orbit (n = 3) to the radius of the first Bohr orbit (n = 1)?

Define drift velocity and mention its relation with electric current.

Define SI unit of current using the force between two parallel current carrying conductors.

Define RMS value of alternating current.

Arrange the following in increasing order of wavelength: X-rays, microwaves, ultraviolet rays, visible rays.

Define power of a lens. If two lenses of power P1 and P2 are placed in contact, what is the equivalent power? **OR** A converging lens of focal length f is kept in contact with a diverging lens of focal length –2f. Find focal length of combination.

Ground state energy of hydrogen atom is –13.6 eV. What are the kinetic and potential energies of electron in this state? **OR** Define Bohr's radius and what is its value?

Based on energy band diagram what makes a: (a) semiconductor, (b) insulator? **OR** Name any two dopants to make intrinsic semiconductor: (a) p-type, (b) n-type.

What is total internal reflection? Write conditions for total internal reflection.

What is photoelectric effect? Explain effect of frequency of incident radiation on stopping potential. **OR** Explain de-Broglie hypothesis, and derive expression for de-Broglie wavelength.

Draw the circuit diagram of half wave rectifier and explain its output waveform.

Find: (i) Equivalent capacitance between A and B, (ii) Total charge, and (iii) Total Energy Stored. C1, C2, C3 and C4 each equal to 10 µF. **OR** An electric dipole is consist of ±50 µC charge with dipole length 20 cm. Calculate electric field due to this dipole at a distance of 30 cm from each charge.

Calculate the internal resistance of a battery: If with an external resistance of 2 Ω it gives a current of 1 A and with external resistance 5 Ω it gives current of 0.5 A.

Write principle of moving coil galvanometer. Explain its working and how it can be used made more sensitive? **OR** What is magnetic susceptibility? An iron rod of magnetic susceptibility 5 × 10³ is inserted in a solenoid having 6000 turns per meter and carries a current of 2 A. Calculate: (i) magnetic intensity, (ii) magnetic flux density, at the centre of solenoid. What will be these values when iron rod removed from the solenoid?

Explain Huygens' principle, using it prove Snell's law of refraction. **OR** Derive Lens Maker's Formula for convex lens using new cartesian sign conventions.

What is AC generator? Write it's principle and describe in detail about the functioning. **OR** What is Phasor Diagram? How it is used to solve LCR series circuit? Derive expression of impedance.