## Tips for Physics & Sample ISC Question

The quantum of success is measured by competitive examinations in today’s competitive world. Science has become the need of the hour and PHYSICS the core element to a successful career.

Smart work is the cutting edge in the BOARD examination. Revision is the uniform formula that leads to a competitive nature.

**The 3D features of revision must be followed .**

- Revise important formulae
- Revise derivation based on definition of physical quantities
- Revise graphs and diagrams.

The ISC examinations are the testing grounds of the application based on theories that leads the way to the competitive arena. One should follow a strict time management chart where knowledge is put to practical use and not confined to the pages of the book.

As the saying goes “ NO pain no gain” meticulous study with terms and terminologies paves the key to success.

For the board examination, you should stick to scope of syllabus. Beyond it will give knowledge but less time to revise.

For example

The application of Biot Savart’s law is for straight conductor carrying current, circular loop and for the point on the axis of the coil carrying current. Similarly Ampere’s circuital law is for infinitely long conductor and long solenoid.

In LCR use phase diagram only.

Kirchhoff’s law is for balance Wheatstone’s bridge and for the circuits with two loops and maximum five resistors/capacitors in circuits. Higher level problems will lead to unnecessary practice for the board exam.

In section ‘C’ numerical are mostly based on the formula E = hc/λ , λ = h/mv for matter wave, direct relation for wave length λ = 1237.5/V nm (for radiation), λ = 1.227/ √V nm for matter
waves. Empirical formula for wave length of the spectral lines of Hydrogen, binding energy relations etc. No numerical from semiconductor device.

In section ‘B’ focus on electromagnetic spectrum and wave optics as this part has limited question to revise.

For practical examination, follow instructions carefully. Don’t go beyond the instructions. Clear the concept of decimal place, significant figures, best fit line and marking of the origin in graph.

**Some practice questions for board examination**

**PHYSICS (PAPER – 1)**

**TIME: 3:00 Hrs.**

** Maximum marks 70**

** Time given at the head of the paper is for writing.**

** Extra 15 minute is given to read the question. You must NOT write anything during first 15 minute.**

** Marks for the question and the subparts of the questions are given in the brackets.**

** Write the answers of all parts of a question at the same place.**

** All questions are compulsory from part I.**

** Answer ten questions from part II choosing four from section ‘A’ & three from each section ‘B’ and ‘C’**

** Material to be supplied: log tables including trigonometric functions.**

** A list of useful constants is given at the end of this paper.**

**Part – I**

** (All questions are compulsory)**

**Question 1. (Only one choice is correct)**

i]A moving coil galvanometer can be used as a voltmeter by connecting ;:

a.Low resistance in series

b.High resistance in parallel

c.High resistance in series

d.Low resistance in parallel

ii]The loss of power in transformer can be reduced by

a.Using the laminated core of soft iron

b.Using the solid steel core

c.Increasing the number of turn in primary

d.Increasing the a.c voltage input.

iii]According to photo electric effect the nature of light is:

a.Longitudinal wave

b.Transverse wave

c.Electromagnetic wave as well as particle

d.Particle.

iv]The final image formed by the microscope with respect to object is:

a.Real and inverted

b.Virtual and inverted

c.Real and erect

d.Virtual and erect

v]The maximum spectral that can be produced by electron in excited state 10. The energy level in which the electron present is:

a.4 b. 5 c. 6 d. cannot be determined

**Question 2. (write answer in brief and to the point)**

i] 0.6 m long straight conductor is moving with speed 7m/s in the magnetic field 0.9T. Find the maximum induced e.m.f.

ii] Define one Henry.

iii] Give circuit diagram for the use of Zener diode as automatic voltage regulator.

iv] What is the frequency of radiation of wave length 500nm?

v] Write the relation between half-life and average life.

vi] Write the relation for the resolving power of the telescope.

vii] Give the difference between the diamagnetic and the paramagnetic substance with respect to magnetic susceptibility.

viii] Find energy stored if a capacitor of capacity 250nF is given100 V.

ix] Write truth table of AND gate for two inputs.

x] Draw the diagram for the equipotential surface.

xi] If power of a lens is 2D then what is magnifying power?

xii] Why is colour of the sky blue?

xiii] How will the angle of deviation change if the angle of prism is doubled?

xiv] In a spherical region potential is zero at a given point, and then electric field must be zero at that point. State if the statement is true by giving the correct
region to support your answer.

xv] What is the significance of Davisson and Germer’s experiment?

**PART – II**

**Section ‘A’**

** (Answer four questions from this section)**

**Question 3.**

a.Connect three capacitors of capacities 3nF, 3nF and 6nF to get 5nF.

b.State Gauss’s theorem. If a point charge 2.0nC is placed at the centre of the cube then find the electric flux through one surface.

**Question 4.**

a.Define electric potential. Write expression to get electric potential at a point due to a point charge.

b.Write the properties of electric lines of forces. 2x 10 – 19 C charge cannot be produced , why?

**Question 5.**

a. State and explain Kirchhoff’s law.

b.Find the expression for the magnetic flux density at the centre of the coil of ‘N’ turns and radius ‘R’ if ‘I’ current is flowing through the coil.

**Question6.**

a.Draw the labeled diagram to find the internal resistance of cell using the potentiometer.

b.If the relative permeability of Aluminium is 1.000022 then find the value of its magnetic susceptibility. Write the unit of magnetic dipole moment.

**Question 7.**

a.If the current through the coil is increases from 0 to 5A in 0.2 second 60V e.m.f is induced in a set of two coils. Find the mutual inductance.

b.In the LCR circuit the p.d across the inductor, capacitor and the resistor are respectively 450V, 250V and 150V. The resistance is 20? Find the peak value of a.c source, reactance of each and the impedance.

**Question 8.**

a.Find the current in the circuit given.

b.What are the magnetic elements of earth? Define them.

**Section ‘B’**

(Answer three questions from this section)

**Question 9.**

a.Arrange all electromagnetic radiation in decreasing order of the wave length. How the electric vector E ? , magnetic vector B ? and the direction of motion of the propagation of radiation are oriented. Which parts of the
radiation are used in the wave communication?

b.A certain monochromatic light travelling in air is incident on glass plate at a polarizing angle. Angle of refraction is found to be 32degree. Calculate the polarizing angle and the refractive index of glass.

**Question 10.**

a.Calculate the angle of minimum deviation for the regular prism if the refractive index is 1.6 for violet colour. How will the angle of minimum change if the colour of light is changed?

b.Find the focal length of the lens if object placed at 30cm forms virtual image at 15 cm. write the nature of the lens.

**Question 11.**

a.What is the use of optical fiber? Draw the ray diagram of an image formed by a telescope with image at the infinity.

b.Draw the ray diagram to correct the defect myopia. Give diagram only, label correctly but don’t give explanation.

**Question 12.**

a.A microscope consists of lenses of focal length 2.0cm and 5.0cm. for final image at 25.0cm if object is at 2.2cm from lens then find the magnifying power.

b.Write the theory of secondary wavelets.

**Section ‘C’**

** Answer any three question**

**Question 13.**

a.Name the series of lines in which ultra violet region is obtained. Write Bohr’s formula for the wavelength of visible light, emitted by hydrogen and explain the meaning of each and every symbol used.

b.Write the equation for pair production and the pair annihilation.

**Question14.**

a.State the law of radioactive disintegration. For the number of half-lives ‘m’ derive the relation N/N_0 = (1/2)m.

b.Draw the maximum kinetic energy and frequency graph for the photoelectric effect. How will you get Planck’s constant from the graph?

**Question 15.**

a.In the given nuclear reaction, calculate the energy released in MeV:

(_1^2)H + (_1^2)H ? (_2^3)He +(_0^1)n

Given that the mass of (_1^2)H = 2.015u, mass of (_2^3)He = 3.017u and mass of(_0^1)n = 1.009u. What is the name of this reaction

b.Use several NAND gates to get OR gate. Draw the labeled diagram in support of your answer.

**Question 16.**

a.Explain the formation of N type semiconductor. Use diagram to explain. Why is it better than intrinsic semiconductor?

b.An X – ray tube is operated at 40,000V, calculate the kinetic energy of an electron emitted by the filament when it reaches the target /anode. What is the self-rectification in X – ray tube?

**Mr. Ram Ratan Dubey,**

**HOD, Department of Physics, **

**Hill Top School, Jamshedpur.**