Practice Questions (long type) Of Physics for 12th Board Exam

Practice Questions(long type) Of Physics for 12th Board Exam 2018
1. ELECTROSTATICS

1. Explain with principle, the construction and working of van de graff generator.
           Bihar Board -2011 

2. Find an expression for capacity of a parallel plate capacitor with compound dielectric.
          Bihar Board -2016 
2. Derive an expression for the capacitance of a parallel plate capacitor . If a compound dielectric medium is introduced between the plates of the capacitor , how will the capacitance of the capacitor change ?
          Bihar Board -2010 
3. Define capacitance of a capacitor . Derive expression for stored energy between plates of parallel plate capacitor .Show the energy density between plates of the capacitor can be expressed as 
\[\frac{1}{2}{{\varepsilon }_{0}}{{E}^{2}}\] , where E = electric field between plates.
          Bihar Board -2018 
                                                         OR
 Define capacitance and give its si unit . Prove that the total electrostatic energy stored in a parallel plate capacitor is $\frac{1}{2}C{{V}^{2}}$ . Hence derive the expression for the energy density of the electric field at its base .
          Bihar Board -2010                                                                                                                                                                                                                                                                                                                                                                                                                       3. Define electric flux. State and prove gauss theorem .
          Bihar Board -2015 ,2012 

3. State Gauss theorem . Apply this to obtain the expression for the electric field intensity at a point due to an infinitely long thin, uniformly charged straight wire .
           Bihar Board -2009 
        
4. find out 
(a)Electric field due to uniformly charged thin spherical shell
   (i) on the surface of the spherical shell
   (ii) outside the spherical shell  
   (iii) inside the spherical shell
 (b) Electric find due to charged plane sheet. (c) Electric find due to charged conductor plate. 
(d)Electric find due to charged straight wire.
4. (1) Find the electric potential and then electric field due to an electric dipole by differential relationship between field and potential.
               Bihar Board -2009  

(i ) Define electric intensity . Derive an expression for electric intensity at a point situated on axis of electric dipole.
            Bihar Board -2015 
(ii)find electric field at equatorial position due to an electric dipole .
(iii)find electric potential at axial position due to an electric dipole .
(iv)find electric potential at equatorial position due to an electric dipole .
(v) What is electric dipole ? find an expression for electric potential at any point due to an electric dipole .
          Bihar Board -2019 

(vi)Establish the expression for electric potential at a point due to a small electric dipole.
          Bihar Board -2021 
(viI)find electric field at any point due to an electric dipole .
  

2. CURRENT ELECTRICITY


1. State and explain kirchhoff’s laws. Applying this law ,obtain the balanced 
condition of wheatstone bridge.
           Bihar Board -2019 
                                                OR
 Define kirchhoff’s laws of electrical circuit . Derive an expression for a balanced wheatstone's bridge using kirchhoff’s law .
            Bihar Board -2015 
2. State ohm’s law and verify it.


3. Explain the working, principle of a potentiometer using a diagram and 
(a)Compare the e.m.f. of two cells 
(b) Find out the internal resistance of a cell.

4. Explain the working, principle,construction of a  meter-bridge.


3. MAGNETIC EFFECT OF CURRENT &  MAGNETISM


1. Explain with the help of a diagram the 
principle ,construction and working of a cyclotron.
                 Bihar Board -2012 
                                                                       
2. Explain Biot- savart law. With its help derive an expression for the magnetic field at any point on the axis of a current carrying circular loop.
                Bihar Board -2015 
                                                              
3. Explain Biot- savart law. Derive an expression for the magnetic field at the center of a current carrying circular loop. 
                Bihar Board -2012                                                        
          
3. Write properties of diamagnetic ,paramagnetic and ferromagnetic materials .
                   Bihar Board -2021                                          
                                              OR
   Distinguish among dia, para and ferromagnetic substances.

4. (a) Explain principle and working of a moving coil galvanometer. Derive an expression for current 
sensitivity.
                 Bihar Board -2009 
       (b)Compare between moving coil galvanometer and moving magnet galvanometer .
                 Bihar Board -2009 
5. (a) Describe in brief terrestrial magnetism.


     (b) Discuss modern (Atomic) theory of

magnetism.

6. (i)State ampere’s circuital law. Obtain the expression for magnetic field due to infinite long current carrying straight wire.
     (ii) Using ampere's circuital law, obtain an expression for the magnetic field along the axis of a current carrying solenoid of length L and having N number of  turns.
        
7. Evaluate  force and torque acting on a magnet in an external uniform magnetic field and also find the work done in rotating the magnet in the magnetic field arbitrarily.
             Bihar Board -2010 

7. Find out the expression for magnetic field due to a bar magnet in broad side-on position .
             Bihar Board -2020 
7. Find out magnetic field in axial and equatorial position due to a bar magnet (magnetic dipole).
8. Find time period of a bar magnet oscillating freely in a uniform magnetic field B.
             Bihar Board -2017 

4. ELECTROMAGNETIC INDUCTION & ALTERNATING CURRENT


1. Define alternating current, its peak value and its r.m.s. value. Derive relationship between  them after evaluating the expression for rms value .
                Bihar Board -2011 
2.Find out an expression for root mean square value of an alternating current.
                Bihar Board -2021 
2. Discuss LCR circuit by phasor diagram.


3. (a) Describe construction and working of an AC  generator.


(b) Describe the principle , construction and working of a transformer.
           Bihar Board -2019 
4. What is electromagnetic induction? State faraday's law of electromagnetic induction and his experiments related it.
4.  Define eddy currents .How are the produced 
 ? In what sense are these currents undesirable in a transformer and how are these reduced in a device ? 
           Bihar Board -2011 

5. (a) What do you mean by self indention and mutual induction?


(b) Does the lenz's law obey the law of conservation energy ?
6. Define self inductance and mutual inductance .Find an expression for mutual inductance of two long coaxial solenoids.
          Bihar Board -2016 

5. ELECTROMAGNETIC WAVES


1. What do you mean by displacement current? How would you express Maxwell ampere law using it?



2. What are electromagnetic waves? Describe their properties. What is electromagnetic spectrum?


6. OPTICS


1. What are defects of vision? How are they corrected by using lenses?

                                  click here TO READ 12th physics NCERT short Question & Answer

2. With neat diagram describe the construction and working of a an astronomical telescope  and find its magnifying power.
              Bihar Board -2019 
             

2. Explain with neat diagram ,the working 
of a compound microscope . Obtain an expression for its magnifying power . 
               Bihar Board -2013 
                                                      
3. Find out the expression for magnifying power of  compound microscope.
               Bihar Board -2021 

3. Draw a ray diagram to show image formation of a compound microscope or astronomical  telescope. Derive an expression for magnifying power of your instrument .Explain the applications of your instrument.
                Bihar Board -2009  
3. Define interference. Derive an expression for fringe width (or wavelength of light) in young’s double slit experiment.
4. What is a biprism ? Explain measurement of wavelength of monochromatic light using biprism.     
               Bihar Board -2017 
5. Define Interference . Derive expression for fringe width in Young's double slit experiment .
               Bihar Board -2012 
4. (i)Establish the formula.

            $\frac{1}{f}=(\mu -1)(\frac{1}{{{r}_{1}}}-\frac{1}{{{r}_{2}}})$
               Bihar Board -2012 ,2021 
     (ii)  Derive lens formula for a concave lens.
5. Show for a prism that the refractive index n is given by  .
          $\n=\frac{\sin ({}^{A+{{\delta }_{m}}}/{}_{2})}{\sin ({}^{A}/{}_{2})}$
                   where symbols have their usual meaning.
                  Bihar Board -2013 
                                                     OR
Draw a ray diagram to show the refraction of light through a glass prism .Derive the formula for the determination of refractive index of the material of the prism.
                Bihar Board -2010
6. Establish the formula .
           $\frac{{{\mu }_{2}}}{v}-\frac{{{\mu }_{1}}}{u}=\frac{{{\mu }_{2}}-{{\mu }_{1}}}{R}$
                  Bihar Board -2015 
                                                        OR
A lens having two curved surfaces of radii of curvature \[{{R}_{1}}\] and \[{{R}_{2}}\] is placed as shown in the figure    
                   figure
Prove that  $\frac{{{n}_{3}}}{v}-\frac{{{n}_{1}}}{u}=\frac{{{n}_{2}}-{{n}_{1}}}{{{R}_{1}}}+\frac{{{n}_{3}}-{{n}_{2}}}{{{R}_{2}}}$
7. Explains Huygen’s principle of secondary wavelets and on the basis of this principle establish the law of refraction or reflection .
                 Bihar Board -2018 
                                                OR
How are wave front and secondary wavelets defined 
? Verify laws of reflection or laws of refraction on the basis of Huygen’s wave theory.
                 Bihar Board -2016 
                                                 OR
Write Huygen’s principle of light wave .Prove the law of reflection  or law of refraction on the basis of Huygen’s principle of light wave .
                   Bihar Board -2015, 2013 

                                                   OR
Define wave front and secondary wavelets ? Verify laws of reflection or laws of refraction on the basis of Huygen’s wave theory.
                 Bihar Board -2014 
                                                   OR
Explains Huygen’s wave theory and use it to explain and establish the law of  reflection or refraction .
                 Bihar Board -2011 
8. (a) What do you mean by diffraction of light.
(b) Write the expression for angular position of the first diffraction ring .Obtained after diffraction by circular aperture.
(c) Write the Rayleigh criterion of resolution.

9. 
What do you mean by equivalent lens? Find focal length of equivalent lens of two lenses of focal lengths f1 and f2 and separated by a distance d.
                                                            OR
What do you mean by equivalent lens? Derive an expression for the equivalent focal length of a system of two lenses placed at a certain separation .  
             Bihar Board -2010 

10.Describe 

(a) Simple microscope & compound microscope.

(b) reflecting & refracting telescope.
11. What is dispersive power ? Find the necessary conditions for obtaining deviation without dispersion by two thin prisms .
            Bihar Board -2019 
          
            


7. DUAL NATURE OF MATTER AND RADIATION


1. What do you mean by De Brogli  wave? Describe Davission and Germer’s experiment to demonstrate the wave nature of electron.


2. What is photo electric emission effect ? 
What are the laws of photoelectric emission effect ?  How did Einstein explained these laws of photo electric effect ?
             Bihar Board -2016 

                                                     OR

Write down Einstein’s photoelectric equation and explain the photoelectric effect on its basis.  

           Bihar Board -2015 

         
                                                            OR
 What is photo electric emission effect ? What are the laws of photoelectric emission effect ?  How did Einstein explained the observed facts of photo electric effect ?
             Bihar Board -2014 
                                                              OR
 Explain the phenomena of photoelectric emission ? What are the laws of photoelectric emission effect ? How are they explained by Einstein ?
             Bihar Board -2011 


8. ATOM &  NUCLEUS

1. Describe the principle and construction of a nuclear reactor.
                                               OR
Explain the construction of a nuclear reactor in detail.
              Bihar Board -2009 

2. What is Rutherford's alpha-scattering experiment? State Rutherford's atomic model.

2. What do you mean by half life and average life of a radioactive substance ? Establish disintegration formula 
($N={{N}_{0}}{{e}^{-\lambda t}}$for radioactive substance.
               Bihar Board -2021 
3. What do you mean by radioactivity? Write the nature , properties and difference among  of alpha, beta and gamma rays. 
              Bihar Board -2012 
 

4. Give postulates of 
Bohr’s theory . Explain hydrogen spectrum on the basis Bohr’s theory. 
              Bihar Board -2015 


5.Obtain expressions for velocity, energy and radius of orbit of an electron orbiting in nth orbit.

5. State Bohr’s assumptions to explain the spectra of hydrogen-like atom .Obtain an expression for the total energy of an electron revolving in the nth stationary orbit of an atom.  
               Bihar Board -2010 
9. ELECTRONIC DEVICES


1. What do you mean by logic gates? Describe AND, OR, NOT, NOR, NAND gate with truth table.


2. What are energy bands? How are these formed 
? Distinguish between conductors ,semiconductors, and insulators  on the basis of formation of these bands.
             Bihar Board -2018 
                                                       OR
   Explain the band theory of solids .State how on this basis solids are classified into conductors , insulators and semiconductors .
             Bihar Board -2013 

                                                        OR
  What are energy bands in solids ? How are semiconductors, insulators and conductors classified on the basis of band theory ?
             Bihar Board -2010 
3. Explain    (b) P-type and n-type semiconductor and forward bias and reverse bias of p-n junction diode. 
(c) P-n-p and n-p- n transistor
4. What do you mean by by P-type and N-type semiconductors 
? Explain the working of a P-N junction diode .
                Bihar Board -2020 
4. What is p-n junction diode? How is it used as a rectifier? Describe in brief characteristics of junction transistor.
4. What is Zener diode 
? Explain its uses as voltage regulator. 
                Bihar Board -2012 
5. Explained with the help of labelled diagram the working of a transistor as an oscillator.
               Bihar Board -2019 
                                                               OR     
State the underlying principle of a transistor being used as an oscillating circuit . Draw a circuit diagram showing how the feedback is accomplished by inductive capacitance .Explain oscillator action .
                  Bihar Board -2014 
6. What is rectifier ? How a p-n junction diode can be used in (i) forward biased and (ii) reverse baised mode ? Draw a labelled V-I characteristic of p-n junction diode on a graph.
               Bihar Board -2016 
10. COMMUNICATION SYSTEM


1. What is amplitude modulation? Explain it.
                  Bihar Board -2013 
2. What do you mean by analog and digital signals ?
                  Bihar Board -2013 
2. Give a brief account on the means of communication.  
                 Bihar Board -2013 

3. Write notes on (a) Fax (b) w w w (c) E-commerce (d)Remote sensing (e) Analogue and digital signal (f)MODEM(g)MODULATION and DEMODULATION (h) Antenna (i)signal (j) Band width (k) Chat (l) E-mail (m)Amplitude modulation index.
4. Describe amplitude modulation and frequency modulation . Derive an expression for covering range of transmission antenna. 
           Bihar Board -2016 

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