12th PHYSICS IMP PRACTICE QUESTIONS
FOR MAHARASHTRA
HSC BOARD
CHAPTER 11 TO 16
Chapter 11. Magnetic Materials
1. Explain the directional characteristic of a bar magnet. State its use.
2. Obtain an expression for orbital magnetic moment of an electron revolving about the nucleus of an atom.
OR
Show that orbital magnetic moment of an electron revolving about the nucleus of an atom is proportional to its angular monmentum
3. State formula for gyromagnetic ratio. Find the gyromagnetic ratio of Electron. ( Given: me = 9.1 ×10⁻³¹kg, and e= 1.6 × 10⁻¹⁹ C).
4. What is the gyromagnetic ratio of an orbital electron ? State its dimensions and the SI unit.
5. State the vector form of the formula of orbital magnetic moment of an electron revolving about the nucleus of an atom. State why it is Negative?
6. Obtain the expression for Bohr Magneton. State its value with unit.
7. Explain magnetization of a material.
8. Define magnetization. State its dimensions and the SI unit. OR
Define magnetization. State its formula and SI unit.
9. Define magnetic intensity. State its dimensions and the SI unit.
10. What is the magnetic susceptibility of a medium?
11. Is magnetic susceptibility a dimensionless quantity? Why?
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CHAPTERR 12. ELECTROMAGNETIC INDUCTION
1) Express Faraday-Lenz’s law of electromagnetic induction in an equation form.
2) Determine the motional emf induced in a straight conductor moving in a uniform magnetic field with constant velocity.
3) Find an expression for the power expended in pulling a conducting loop out of a magnetic field.
4) What are eddy currents? State applications of eddy currents.
5) Explain and define the self inductance of a coil.
6) State and define the SI unit of self inductance. Give its dimensions.
7) Obtain an expression for the self inductance of a solenoid.
8) Derive the expression for the energy stored in the magnetic field of an inductor.
9) Obtain an expression for the self inductance of a solenoid.
10) Explain and define mutual inductance of a coil with respect to another coil.
11) Show that the mutual inductance for a pair of inductively coupled coils/circuits of self inductances L1 and L₂ is given by M = K√L1L₂ , where K is the coupling coefficient.
12) What is a transformer? State the principle of working of a transformer.
13) Describe the construction and working of a transformer with a neat labelled diagram.
14) Distinguish between a step-up and a step-down transformers.
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Chapter 13 AC CIRCUITS
1) What is the average or mean value of an alternating emf? Obtain the expression for it.
2) What is the rms value of an alternating current? Find the relation between the rms value and peak value of an alternating current that varies sinusoidaily with time.
3) What is a phasor? What is a phasor diagram ? Illustrate it with an example.
4) An alternating emf e = e₀ sin ωt is applied to a resistor of resistance R.
Write the expression for the current through the resistor. Show the variation of emf and current with ωt.
Draw a phasor diagram to show emf and current.
5) Draw a Phasor diagram showing e and i in the case of a purely inductive circuit.
6) An alternating emf is applied to an LR circuit. Assuming the expression for the current, obtain the expressions for the applied emf and the effective resistance of the circuit. Assume the inductor and resistor to be ideal.
Draw the phasor diagram showing the emf and current.
7) Draw the impedance triangle for a series LCR AC circuit and write the expressions for the im-pedance and the phase difference between the emf and the current.
8) What is an acceptor circuit ? State its use.
9) Explain electrical resonance in an LC parallel circuit. Deduce the expression for the resonant frequency of the circuit.
10) What is a rejector circuit? State its use.
11) How are oscillations produced using an inductor and a capacitor?
12) Explain electrical resonance in an LCR series circuit.
Deduce the expression for the resonant frequency of the circuit.
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Chapter 14 Dual Nature of Radiation and Matter
1) With a neat diagram, describe the apparatus to study the characteristics of photoelectric effect.
2) In the experiment to study photoelectric effect, describe the effects of the frequency and intensity of the incident radiation on the photoelectric current, for a given emitter material and potential difference across the photoelectric cell.
3) Define (1) Threshold frequency (2) Threshold wavelength (3) Stopping potential.
4) State the characteristics of photoelectric effect.
5) Define photoelectric work function of a metal.
6) Write Einstein’s photoelectric equation and explain its various tends. How does the equation explain the various features of the photoelectric effect?
7) Explain wave-particle duality of electromagnetic radiation.
8) State the de Broglie hypothesis and the de Broglie equation.
9) Derive an expression for the de Broglie wavelength associated with an electron accelerated from rest through a potential difference V. Consider the nonrelativistic case.
10) Derive an expression for the de Broglie wavelength.
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Chapter 15 Structure of Atoms and Nuclei
1) Explain Thomson’s model of the atom. What are its drawbacks?
2) Explain Rutherford’s model of the atom. State the difficulties faced by Rutherford’s model of the atom.
3) State and explain the formula that gives wavelengths of lines in the hydrogen spectrum.
4) State the Postulates of Bohr’s atomic model.
5) speed of an electron in a Bohr orbit. Hence, show that it is inversely proportional to the principal quantum number.
6) Derive an expression for the radius of the nth Bohr orbit in an atom. Hence, show that the radius of the orbit is directly proportional to the square of the principal quantum number.
7) Show that the energy of the electron in the nth stationary orbit in the hydrogen atom is Eₙ = -RHch/n².
8) Draw a neat, labelled energy level diagram for the hydrogen atom. Hence explain the different series of spectral lines for hydrogen.
9) Obtain the ratio of the longest wavelength of spectral line in the Paschen series to the longest wavelength of spectral line in the Brackett series.
10) State the limitations of Bohr’s atomic model.
11) On the basis of the de Broglie hypothesis, obtain Bohr’s condition of quantization of angular momentum.
12) State the law of radioactive decay and express it in the exponential form.
OR
State the law of radioactive decay. Hence derive the relation N = N₀e-λt, where the symbols have their usual meanings.
13) Define half-life a radioactive element and obtain the relation between half-life and decay constant.
14) What is meant by average life or mean life of a radioactive species ? How is it related to the half-life?
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Chapter 16 Semiconductor Devices
1) Draw a neat block diagram of a dc power supply and state the function of each part.
OR
With the help of a block diagram, explain the scheme of a power supply for obtaining dc output voltage from ac line voltage.
2) Explain full wave rectifier. State advantages of it.
3) Distinguish between a half-wave rectifier and full-wave rectifier.
4) Explain ripple in the output of a rectifier. What is ripple factor?
5) Explain the action of a capacitive filter with necessary diagrams.
6) What is a photodiode? Explain the I-V characteristics of a photodiode.
7) What is (i) dark current (ii) dark resistance of a photodiode?
8) State any advantages and disadvantages of a photodiode.
9) State any two applications of photodiodes.
10) What is a solar cell ? State the principle of its working. State any four uses of solar cells.
11) State the material selection criteria for solar cells.
12) What is a light-emitting diode (LED)? Describe with a neat diagram the construction of an LED.
13) State any four disadvantages of an LED. State any four applications of LEDs.
14) Explain the working of an npn transistor with a neatly labelled circuit diagram.
15) Draw a neat labelled circuit diagram to study the characteristics of a transistor in common- emitter configuration.
16) What is an amplifier? Draw a neat circuit diagram of a transistor CE- amplifier and explain its working.
17) Define the following logic gates :
(1) AND
(2) OR
(3) NOT.
Give the logic symbol, Boolean expression and truth table of each.
18) Define the logic gates (1) NAND (2) NOR.
Give the logic symbol, Boolean expression and truth table of each.
How are the above gates realized from the basic gates?
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