Download HOLIDAY HOME WORK SUBJECT PHYSICS CLASS XII Q.1 What is

HOLIDAY HOME WORK
SUBJECT PHYSICS
CLASS XII
Q.1 What is the angle b/w the direction of electric field and dipole moment at any
(1) axial point (2) equatorial point
Q.2 A concave lens of refractive index 1.5 is immersed in a medium of µ=1.65 . what is the nature of the
lens?
Q.3 The power factor of an a.c. circuit is 0.5 What is the phase difference between voltage and current
in this circuit?
Q.4 Write two factor by which current sensitivity of moving coil galvanometer can be increased .
Q.5 Sketch electric field lines of force for 2 positive charges (q1>q2) separated by some distance.
Q.6 A cell of emf E and internal resistance r is connected across a variable resistor R. plot variation of
terminal potential V with resistance R.
Q.7 Out of the following identify the materials which can be classified as (1) Paramagnetic
(2) Diamagnetic
(a) Aluminium (b) Bismuth (c) Copper (d) Sodium
Write one property to distinguish between paramagnetic and diamagnetic material .
Q.8 A light bulb is rated at 125W for a 250 V a.c. supply calculate the resistance of the bulb?
Q.9 How will the capacitance of a parallel plate capacitor be affected if
(1) The area of each plate is increased. (2) The distance b/w the plate is increased.
Q.10 A potentiometer wire of length 1m is connected to a driver cell of emf 3v. when a cell of 1.5 v emf
is used in the secondary circuit the balance point is found to be 60 cm on replacing this cell and using a
cell of unknown emf , balance point shift to 80 cm
(a) Calculate unknown emf of cell.
(b) Explain with reason , whether the circuit work if the driver cell is replaced with cell of emf 1v.
(c) Does high resistance R,used in the secondary circuit affect the balance point ? justify
Q.11 Define self inductance of a coil. Show that magnetic energy required to build up a current I in a coil
of self inductance L , is given by 1/2Li2.
Q.12 Give the principal of potentiometer .draw circuit diagram and determine the unknown resistance
of primary cell using it .
Q.13 A potentiometer wire of length 1m has a resistance of 10Ω . it is connected to a 6V battery in series
with a resistance of 5Ω. Determine the emf of the primary cell which gives a balance point at 40cm.
Q.14 (a) A pair of adjacent coils has a mutual inductance of 1.5H. if the current in the one coil changes
from 0 to 20 A in 0.5 sec , what is the change of magnetic flux linkage with the other coil ?
(b) How does the mutual inductance of a pair of coil changes when
(1) The distance b/w the coil is increased
(2) The no. of turns in each coil is decresed
Q.15 State Gauss theorem . and derive electric field intensity due to a positively charged sheet.
Q.16 The oscillating electric field of an electromagnetic wave is given by
Ey=30 sin(2x1011t+300Пx)Vm-1
(a) Obtain the value of wavelength of the electromagnetic wave.
(b) Write down the expression for oscillating magnetic field.
Q.17 What do you mean by TIR effect? Write two necessary condition for it.
Q.18 Derive mirror formula for a concave mirror.
Q.19 An electric dipole of length 4cm, when placed with its axis making angle of 60 owith a uniform
electric field , experience a torque of 4√3 N m. calculate the potential energy of the dipole, if it has
charge±8Nc.
Q.20 (a) Derive the expression for the capacitance of a parallel plate capacitor having plate area A and
plate separation d.
(b) Two charged spherical conductors of radii R’ and R’’ when connected by a conducting wire acquire
charge q’ and q’’ respectively . find the ratio of their surface charge densities in terms of their radii.
Q.21 What is the constituent radiation of electromagnetic spectrum which is used for
(1) aircraft navigation.
(2)studying crystal structure . write the frequency range for each.
Q.22 (a) A 60 µF capacitor is connected to a 110V,60Hz ac supply. Determine the rms value of current in
the circuit.
(b)What is the net power absorbed by the circuit in a complete cycle?
Q.23 While performing an experiment on determination of unknown resistance using a meter bridge ,
Raju obtained deflection in the galvanometer in the same direction even after repeated adjustment in
the circuit and thus could not get any results. In order to avoid getting noticed and scolded by the
teacher, he pretended having performed the experiment and copied the reading obtained by another
student .Answer the following questions based on above information:
(a) Write the possible reasons for getting the deflection in the galvanometer in the same direction.
(b) Which two values is raju violating in copying the reading from another student?
(c) What ,in your opinion, should have raju done in the given circumstances.
Q.24 A toroid has a core of inner radius 20cm and outer radius 22cm ,around which 4200 turns of a wire
are wound . if the current in the wire is 10A, what is the magnetic field (1) outside the toroid , (2) inside
the core of the toroid , and (3) in the empty space surrounded by the toroid .
What is solenoid? A solenoid 50 cm long has 4 layers of winding of 350 turns each . the radius of the
lowest layer is 1.4 cm. if the current carried is 6.0 A, estimate the magnitude of magnetic flux density
(a) near the center of solenoid on its axis, (b) near the ends on its axis, (c) outside the solenoid near its
center.
Q.25 Derive prism formula. Show variation between incidence angle and angle of deviation for a prism.
Derive lens maker formula for double convex lens . state assumptions made and sign conventions.
Q.26 Derive an expression of torque on a magnetic dipole placed in a uniform magnetic field with
suitable diagram . Hence define magnetic dipole moment .A bar magnet placed with its axis at 300 to
uniform magnetic field of 0.2 T experience a torque of 0.06Nm . calculate the magnetic moment of
magnet.
(1) Distinguish the magnetic properties of a dia, para, ferro magnetic substance in terms of
(1 ) susceptibility (2) magnetic permeability (3) coercivity
Give two example of each substance.
(2) The susceptibility of magnetism at 300K is 1.2x10-5. At what temperature will the susceptibility be
equal to 1.44x10-5?
Q.27 Draw the transfer characteristic of a base based transistor in common emitter configuration.
Explain briefly the meaning of the term active region, cut off region ,saturation region in these
characteristic . For what practical use ,do we use transister in this active region ?
Q.28 Draw circuit diagram to study the characteristic of npn transistor in CE configuration . sketch input
and output characteristic for such configuration .HOW current gain of transistor is calculated from
output characteristic
Q.29 Draw circuit diagram of full wave rectifier using P-N junction diode . Explain its working and show
output ,input wave form
Q.30 Draw circuit diagram of CE AMPLIFIER USING NPN transistor. Define voltage gain, current gain .
how input voltage and output voltage are out of phase?