# MODEL PAPERS

## Friday, 17 July 2020

GOA Board HSSC Model Papers 2021, Design of the Question PANDOLE STUDY  Goa board Exam 2020 - 2021 Most important Questions For Exam 2021|Class- 12th goa board previous year question papers , goa board ssc question papers 2018 english goa board question papers for 12th commerce 2017 Model papers Sample papers Download In hindi |

Subject - physics

Time - 3 hours /  maximum marks: 70

1.  An  observe looks at  a tree of height  15 m  with a telescope of  magnifying power 10.  Appears  to him
(A)  10 times  taller
(B)  15 times taller
(C) 15 time nearer
(D) 10 time nearer

2.A  uniform  wire of length l  and  resistance R  is gradually  stretched by  applying a force. Its  resistance  R versus  length l  graph will be

3.In  an AC  circuit,  the voltage applied is E=E0sint. The Resulting current in the  circuit is
I= Iosin(t-/2).Power constumption  in  the circuit is

4. in the nuclear reaction

The  mass number (A)  and charge number (Z)  of nucleus x  have the respective value
(A) 234,88
(B) 230,92
(C) 230,90
(D) 228,90

5.  write the function of a  repeater used in communication system.
6. An ebonite Rod is rubbed  with fur. Is  there any transfer of mass from the fur To the rod ?Justify your answer.

7.  the barrier  potential of a  silicon p-n  junction is 0.7.v. can  we  measure  it Using a voltmeter ?

8. What is the  importance of modulation index in  communication system ?

## GOA Board HSSC Model Papers 2021, Design of the Question PANDOLE STUDY

Section-  B

9. Two Short magnets  having dipole  movement M  each are fastened  perpendicularly  at their centrers as shown  in the  figure. find the magnitude of the magnetic field of the combination at  distance d  from the centre  on bisector at  right angle to the plane of the system.

1o. Using  einstein’s  Photoelectric equation show  how one can  determine the value of (i)  Planck’s  content and (ii)  work function of the photo- sensitive material used.

11. A Plane is fixed at a  height h   above  from the  bottom  of  a  beaker.  the beaker contains water  of  refractive  in index index, Height d as shown  in the figure.  find the position of the image off the bottom as  formed by the  mirror

12.  figure show a graph of  Coulomb  force (F)  versus 1/r2  for two   pairs of point charges in  two different situations: (a)  two charges are q1 And q2  and (b)  two charges are q1  and q3.
(q1 and q3).  Here ‘r’  is the  separation between the.  Charges.  If q1  is positive and last in magnitude,

(i) What is the nature i.e. sigh  of q2  and q3  respectively ?

(ii)  plot a graph  Sewing variation  of force  between q1  and (q2+q3)  with 1/r2.
Or
Two  large  conducting plane   plates p1  and p2  are kept in  contact between two identical metal balls having -q  and +q  charges as shown  in the figure

(i)Sketch electric field lines between the balls  and plates.
(ii)  what happens when the plates are released ?

13. Derive the expression  for  the de-Broglie  wavelength of electron accelerated  through a potential difference of v  volts.

14.  draw a plot of binding energy per nucleon (BE/A) vs  mass number A for Nuclei  in the range 2 A250.

15. The electric mains  in a  house is rated 220 v, 50 Hz ,  write down the  question for the instantane ous  voltage.  what is the time taken by the voltage to change from its maximum value to its rms  value ?

### GOA Board HSSC Model Papers 2021, Design of the Question PANDOLE STUDY

Section- C

16. (i) State principle of working of a moving coil galvanometer.
(ii) why  do we  need  radial magnetic field in this device ?
(iii)  while  using a galvanometer as a  voltmeter a  high resistance  is connected in series will using  a galvanometer  as an  ammeter a shount  is  used. give reason.

17.  define drift  velocity of free electrons  in a conductor, establish the relationship  between drift velocity and the electric current.
Or
State kirchhoff’s  rule  for  an  electrical network and  Derive the condition  off balance in a wheatstone  bridge.

GOA Board HSSC Model Papers 2021, Design of the Question PANDOLE STUDY

18.  what is the importance of coherent  source in young’s  double slit experiment ?  obtain the  pression for the  fringe width  in terms of wave  length Of   light, distance from the  slits to the  screen D  and separation between the two slide d.

19. (i) Two Straight long parallel conducting wire carry current I1  and I2  in the same direction. deduce an  expression for force per unit length between them.

(ii)  use this expression to define SI  unit of current.

(iii)  sketch the pattern  of magnetic field lines  around them.

20. (a)  draw a sketch  play propagating in  space.  also indicate the direction of the oscillating electric and  magnetic field   associated  with the  wave. what determines  the speed of propagation  of electromagnetic wave ?

GOA Board HSSC Model Papers 2021, Design of the Question PANDOLE STUDY

(b)  how are electromagnetic waves produced by oscillating charges ?

21. explain with the help of labeled ray  diagram, the working of a compound microscope. Why  must  Both  the objective and  eye piece  of compound microscope have thought focal lengths ?
22. (a) Using bohr’s  postulate of  quantization of orbital  angular momentum, show  that the  circumference  of the orbit of electron in the nth  state of hydrogen atom  is n times  the de-Broglie  wavelength associated with it.

(b)  calculate the shortest wavelength of the line emitted in the Balmer  series of hydrogen spectrum.

23.  state two difference between n- type  and p- type semiconductors.
A  specimen  of pure semiconductor s  is connected in series with a Variable resistance R,  an  Amita and a cell  how would you change the  value of R to Keep the reading of the  Ammeter  constant, when same is heated ? explain.

24. Figure shows the experimental setup of a matre bridge.  the Galvanometer Shows  no  deflecation  when movable contact (j) touches  the meter  bridge  wire  at D such  that AD = 40 cm.
If a 30 Resistor is connected  in parallel with x2,  the  balance  Point  shifts by 10 cm.
(i)  find the value of x1  and x2
(ii)  find the position of balance point, if 30 resistor is Connected in parallel with  x1.

#### GOA Board HSSC Model Papers 2021, Design of the Question PANDOLE STUDY

25. With the help of a  tablet circuit diagram,  briefly  explain the working of a common emitter n-p-n  transistor amplifier.  define its voltage gain.
Or
draw circuit diagram of a full wave rectifier using p-n  Junction diodes.  explain its working and so the input  and output waveforms.

26.  what is the frequency range at  which TV   signals  IR transmitter and why ?
the height of a TV  Tower is 80  metre  calculate the range up  to which signals from the tower can be received.

Section- D
27. (a)  using phasor  diagram, derive an  expression for the impedance  of a  series LCR  circuit.

(b)  give the reading in the  voltmeter and ammeter of the circuit shown in the figure.

Or

(a) Derive the expression for the mutual inductance  of two  long coaxial solenoids, Each of length l , wound one  over the other,  the inner solenoid has radius r1  and N1  number of turns and the outer solenoid  has radius r2  and N2  number of turns.

(b)  figure shows an Arrangement by which the current flows in the  bulb (B)  connected with coil Y   When AC is passed through   coil x .  explain (i)  why the bulb length up  and (ii)  if a copper sheet is  inserted in the gap  between  the coil x  and Y,  how the brightness of the bulb would change.

#### GOA Board HSSC Model Papers 2021, Design of the Question PANDOLE STUDY

28. (a) Draw a ray diagram  to show the formation  of a real image of a point  object due to a convex  sperical  refracting surface,  when a Ray of light  is  travelling from rarer  medium  of  refractive 1to a  denser medium of  refractive index 2. Hence Derive the relation between object ,  distance,  image distance and radius of  curvatere  of the  spherical surface.

(b) An  object is  placed  in front of right angled  asosceles Prism ABC   in TWO  positions   as shown . The reason is made of crown glass with critical angle of  41° trace  the path  of the rays from p and Q in each of the two cases.

Or
(a) Distinguish between unpolarized  and linearly  polarized  light.
How  is  linerly  polarized  light produced ?

(b)  unpolarised light  is incident on  surface  separating  two  media  of refractive indices 1 and 2 (1<2). obtain  the condition  use diagram they gets completedly  polarized.

29. (a) Define  electrostatic  potential at a point .  derive expression for the electrostatic potential energy of a pair of charge q1  and q2  kept r  distance apart in free space.

(b)  an electric dipole  consists of +1 CAnd -1 CCharges kept  10 cm apart.  if it experiences

(i) Its Organisation in the field,
(ii)  potential energy of the dipole,
(iii)  work done in turing it  from it initial orientation to its orientation  in  unstable  equilibrium.

Or
(a)Define capacitance of  capacitor. Obtain  expression for the  equivalent  capacitance of to  capacitor C1  and C2  connected in parallel across a battery .

(b)  A  parallel plate capacitor is  connected across a battery, after sometime, the battery is disconnected. the plates are pulled  apart it twice the  initial  separation and  dielectric slab of  dielectric constant k=10  if kept inside the capacitor  filling the entire space  between its  plates,  how will the
(i) energy stored in the capacitor,
(ii)  capacitance of the capacitor and
(iii)  electric field between the   plates affected in this cases? Justify your answer where in each case.
.m

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