## Monday, 17 October 2016

### CLASS 12 CBSE PHYSICS ELECTROSTATICS AND CURRENT ELECTRICITY ONE MARK QUESTIONS

1. Draw schematically an equipotential surface of a uniform electrostatic field along x-axis.
2. Sketch field lines due to (i) two equal positive charges near each other (ii) a dipole.
3. Name the physical quantity whose SI unit is volt/meter. Is it a scalar ora vector quantity?
4. Two point charges repel each other with a force F when placed in water of dielectric constant 81.
What will the force between them when placed the same distance apart in air?
5. Electric dipole moment of CuSO4 molecule is 3.2 × 10–32 Cm. Find theseparation between copper
and sulphate ions.
6. Net capacitance of three identical capacitors connected in parallel is 12microfarad. What will be
the net capacitance when two of them areconnected in (i) parallel (ii) series?
7. A charge q is placed at the centre of an imaginary spherical surface. What will be the electric flux
due to this charge through any half of the sphere.
8. Draw the electric field vs distance (from the centre) graph for (i) a long charged rod having linear
charge density λ <; 0 (ii) spherical shell of radius R and charge Q > 0.
9. Diagrammatically represent the position of a dipole in (i) stable (ii) unstable  equilibrium when
placed in a uniform electric field.
10. A charge Q is distributed over a metal sphere of radius R. What is the electric field and electric
potential at the centre?
11. If a body contains n1 electrons and n2 protons then what is the total charge on the body?
12. What is the total positive or negative charge present in 1 molecule of water.
13. How does the energy of dipole change when it in rotated from unstable equilibrium to stable equilibrium in a uniform electric field.
14. Write the ratio of electric field intensity due to a dipole at a point on the equatorial line to the field
at a point at a point on the axial line, when the points are at the same distance from the centre of
dipole.
15. Draw equipotential surface for a dipole.
16. An uncharged conductor A placed on an insulating stand is brought near a charged insulated conductor B. What happens to the charge and potential of B?
17. A point charge Q is placed at point O shown in Fig. Is the potentialdifference VA – VB positive,
negative or zero, if Q is (i) positive (ii) negative charge.
18. An electron and proton are released from rest in a uniform electrostatic field. Which of them will
have larger acceleration?
19. In an uniform electric field of strength E, a charged particle Q moves point A to point B in the
direction of the field and back from B to A. Calculate the ratio of the work done by the electric
field     in taking the charge particle from A to B and from B to A.
20. If a dipole of charge 2μC is placed inside a sphere of radius 2m, what is the net flux linked with
the sphere.
21. Four charges + q, –q, +q, –q are placed as shown in the figure. What is the work done in
bringing a test charge from ∞ to point 0.
22. Calculate number of electric field lines orignating from one coulomb charge.
23. If the metallic conductor shown in the figure is continuously charged from which of the points
A,B,C or D does the charge leak first. Justify.
24. What is dielectric strength? Write the value of dielectric strength of air.

25. Two charge –q and +q are located at points A (0, 0, –a) and B(0, 0, +a). How much work is done
in moving a test charge from point (b, 0, 0) to Q (–b, 0, 0)?
26. If an electron is accelerated by a Potential difference of 1 Volt, Calculate the gain in energy in
Joule and electron volt.

27. Draw schematically the equipotential surface corresponding to a field that uniformly increases in
magnitude but remains in a constant (say z) direction.
28. Without referring to the formula C = ε0A/d. Explain why the capacitance of a parallel plate
capacitor reduces on increasing the separation between the plates?
29.Draw field lines to show the position of null point for two charges + Q1 and –Q2 when magnitude
of Q1 > Q2 and mark the position of null point.
30. How does the relaxation time of electron in the conductor change when temperature of the conductor decreases.
31. Sketch a graph showing variation of resistivity with temperature of (i) Copper (ii) Carbon.
32. The emf of the driver cell (Auxillary battery) in the potentiometer experiment should be greater than emf of the cell to be determined. Why?
34. You are required to select a carbon resistor of resistance 47kΩ ± 10% from a large collection. What should be the sequence of color bands used to code it?
36. Two wire one of copper and other of manganin have same resistance  and equal length. Which wire is thicker?
37.Why is the potentiometer preferred to a voltmeter for measuring emf of a cell?
38. How can a given 4 wires potentiometer be made more sensitive?
39. Why is copper not used for making potentiometer wires?
40. A copper wire of resistance R is uniformally stretched till its length is increased to n times its original length. What will be its new resistance?
41. What is the largest voltage that can be safely put across a resistor marked 196Ω, 1W?
42. When does the terminal voltage of a cell become (i) greater than its emf (ii) less than its emf?

43.A car battery is of 12V. Eight dry cells of 1.5 V connected in series also give 12V, but such a
combination is not used to start a car. Why?
44. Two electric lamps A and B marked 220V, 100W and 220V, 60W respectively. Which of the two
lamps has higher resistance?
45. Resistors of high value are made up of carbon. Why ?
46. A 16Ω thick wire is stretched so that its length becomes two times.Assuming there is no change in density on stretching. Calculate the resistance of new wire.
47. State the Condition under which the terminal potential difference across
a battery and its emf are equal.

48. State the Condition for maximum current to be drawn from a Cell.

## Saturday, 15 October 2016

### CLASS 11 CBSE PHYSICS OSCILLATION AND WAVES ONE MARK QUESTIONS

1. How is the time period effected, if the amptitude of a simple pendulum is increased?
2. Define force constant of a spring.
3. At what distance from the mean position, is the kinetic energy in simple harmonic oscillator equal to potential energy?
4. How is the frequency of oscillation related with the frequency of change in the of K.E and P.E of the body in S.H.M.?
5. What is the frequency of total energy of a particle in S.H.M.?
6. How is the length of seconds pendulum related with acceleration due gravity of any planet?
7. If the bob of a simple pendulum is made to oscillate in some fluid of density greater than the density of air (density of the bob density of the fluid), then time period of the pendulum increased or decrease.
8. How is the time period of the pendulum effected when pendulum is taken to hills or in mines?
9. A transverse wave travels along x-axis. The particles of the medium must move in which direction?
10. Define angular frequency. Give its S.I. unit.
11. Sound waves from a point source are propagating in all directions. What will be the ratio of amplitudes at distances of x meter and y meter from the source?
12. Does the direction of acceleration at various points during the oscillation of a simple pendulum remain towards mean position?
13. What is the time period for the function f(t) = sin ωt +cos ωt may represent the simple harmonic motion?
14. When is the swinging of simple pendulum considered approximately SHM?
15. Can the motion of an artificial satellite around the earth be taken as SHM?
16. What is the phase relationship between displacement, velocity and accelection in SHM?
17. What forces keep the simple pendulum in motion?
18. How will the time period of a simple pendulum change when its length is doubled?
19. What is a harmonic wave function?
20. If the motion of revolving particle is periodic in nature, give the nature of motion or projection of the revolving particle along the diameter.
21. In a forced oscillation of a particle, the amplitude is maximum for a frequency w1 of the force, while the energy is maximum for a frequency w2 of the force. What is the relation between w1 and w2?
22. Which property of the medium are responsible for propagation of waves
through it?
23. What is the nature of the thermal change in air, when a sound wave propagates through it?
24. Why does sound travel faster in iron than in water or air?
25. When will the motion of a simple pendulum be simple harmonic?
26. A simple harmonic motion of acceleration ‘a’ and displacement ‘x’ is represented by a + 4π2x = 0. What is the time period of S.H.M?
27. What is the main difference between forced oscillations and resonance?
28. Define amplitude of S.H.M.
29. What is the condition to be satisfied by a mathematical relation between time and displacement to describe a periodic motion?
30. Why the pitch of an organ pipe on a hot summer day is higher?
31. Under what conditions does a sudden phase reversal of waves on reflection takes place?

### CLASS 11 CBSE PHYSICS KINETIC THEORY OF GASES ONE MARK QUESTIONS

1. Write two condition when real gases obey the ideal gas equation (PV =nRT). n → number of mole.
2. If the number of molecule in a container is doubled. What will be the effect on the rms speed of the molecules?
3. Draw the graph between P and 1/V (reciprocal of volume) for a prefect gas at constant temperature.
4. Name the factors on which the degree of freedom of gas depends.
5. What is the volume of a gas at absolute zero of temperature?
6. How much volume does one mole of a gas occupy at NTP?
7. What is an ideal gas?
8. The absolute temperature of a gas is increased 3 times what is the effect on the root mean square velocity of the molecules?
9. What is the Kinetic Energy per unit volume of a gas whose pressure is P?
10. A container has equal number of molecules of hydrogen and carbon dioxide. If a fine hole is
made in the container, then which of the two gases shall leak out rapidly?
11. What is the mean translational Kinetic energy of a perfect gas molecule at temperature T?
12. Why it is not possible to increase the temperature of a gas while keeping its volume and pressure
constant.
13. When an automobile travels for a long distance the air pressure in the tyres increases. Why?
14. A gas storage tank has a small leak. The pressure in the tank drop more quickly if the gas is hydrogen than if it is oxygen. Why?
15. Why the land has a higher temperature than the ocean during the day but a lower temperature at night.
16. Helium is a mixture of two isotopes having atomic masses 3g/mol and 4g/mol. In a sample of helium gas, which atoms move faster on average?
17. State Avogadro’s law. Deduce it on the basis of Kinetic theory of gases.
18. Although the velocity of air molecules is nearly 0.5 km/s yet the smell of scent spreads at a much slower rate why.
19. The root mean square (rms) speed of oxygen molecule at certain temperature ‘T’ is ‘V’. If temperature is doubled and oxygen gas dissociates into atomic oxygen what is the speed of atomic oxygen?
20. Two vessels of the same volume are filled with the same gas at the same temperature. If the pressure of the gas in these vessels be in the ratio 1 : 2 then state
(i) The ratio of the rms speeds of the molecules.
(ii) The ratio of the number of molecules.
21. Why gases at high pressure and low temperature show large deviation from ideal gas behaviour.
22. A gas is filled in a cylinder fitted with a piston at a definite temperature and pressure. Why the pressure of the gas decreases when the piston is pulled out.

### CLASS11 CBSE PHYSICS THERMODYNAMICS ONE MARK QUESTIONS

1. Why spark is produced when two substances are struck hard against each other?
2. What is the specific heat of a gas in an isothermal process.
3. On what factors, does the efficiency of Carnot engine depend?
4. What are two essential features of Carnot’s ideal heat engine.
5. Plot a graph between internal energy U and Temperature (T) of an ideal gas.
6. Refrigerator transfers heat from cold body to a hot body. Does this violate the second law of thermodynamics.
7. Is it possible to increase the temperature of gas without giving it heat?
8. Can the specific heat of a gas be infinity?
9. Out of the parameters : temperature, pressure, work and volume, which parameter does not characterise the thermodynamics state of matter?
10. Why a gas is cooled when expanded?
11. On what factors, the efficiency of a Carnot engine depends?
12. Heat is supplied to a system, but its internal energy does not increase.
What is the process involved?
13. Under what ideal condition the efficiency of a Carnot engine be 100%.
14. Which thermodynamic variable is defined by the first law of thermodynamics?
15. If coefficient of performance of a refrigerator a constant quantity?
16. What is the efficiency of carnot engine working between ice point and steam point?
17. Heat cannot flow itself from a body at lower temperature to a body
at higher temperature is a statement or consequence of which low of thermodynamics?
18. What is the specific heat of a gas in an adiabatic process.

### CLASS11 CBSE PHYSICS PROPERTIES OF MATTER ONE MARK QUESTIONS

1. Define term (i) stress (ii) strain
2. Differentiate the properties plasticity and elasticity of material
3 Draw stress - strain curve for elastomers (elastic tissue of Aorta)
4. How are we able to break a wire by repeated bending?
5. What is the value of bulk modulus for an incompressible liquid?
6. Define Poisson’s ratio? Does it have any unit?
7. What is elastic fatigue?
8. Why is it easier to swim in sea water than in the river water?
9. Railway tracks are laid on large sized wooden sleepers. Why?
10. The dams of water reservoir are made thick near the bottom. Why?
11. Why is it difficult to stop bleeding from a cut in human body at high altitude?
12. The blood pressure in human is greater at the feet than at the brain.Why?
13. Define coefficient of viscosity and write its SI unit.
14. Why machine parts get jammed in winter?
15. Why are rain drops spherical?
16. Why do paints and lubricants have low surface tension?
17. What will be the effect of increasing temperature on (i) angle of contact
(ii) surface tension.
18. For solids with elastic modulus of rigidity, the shearing force is proportional to shear strain. On what factor does it depend in case of fluids?
19. How does rise in temperature effect (i) viscosity of gases (ii) viscosity of liquids.
20. Explain why detergents should have small angle of contact?
21. Write the dimensions of coefficient of viscosity and surface tension.
22. Obtain a relation between SI unit and cgs unit of coefficient of viscosity.
23. Explain, how the use of parachute helps a person jumping from an aeroplane.
24. Why two ships moving in parallel directions close to each other get attracted?
25. Why the molecules of a liquid lying near the free surface possess extra energy?
26. Why is it easier to wash clothes in hot water soap solution?
27. Why does mercury not wet glass?
28. Why ends of a glass tube become rounded on heating?
29. What makes rain coats water proof?
30. What happens when a capillary tube of insufficient length is dipped in a liquid?
31. Does it matter if one uses gauge pressure instead of absolute pressure in applying Bernoulli’s equation?
32. State Wein’s displacement law for black body radiation.
33. State Stefan Boltzmann law.
34. Name two physical changes that occur on heating a body.
35. Distinguish between heat and temperature.
36. Which thermometer is more sensitive a mercury or gas thermometer?
37. Metal disc has a hole in it. What happens to the size of the hole when disc is heated?
38. Name a substance that contracts on heating.
39. A gas is free to expand what will be its specific heat?
40. Is the bulb of a thermometer made of diathermic or adiabatic wall?
41. What is the absorptive power of a perfectly black body?
42. At what temperature does a body stop radiating?
43. If Kelvin temperature of an ideal black body is doubled, what will be the
effect on energy radiated by it?
44. In which method of heat transfer does gravity not play any part?
45. Give a plot of Fahrenheit temperature versus Celsius temperature
46. Why birds are often seen to swell their feather in winter?
47. A brass disc fits snugly in a hole in a steel plate. Should we heat or cool the system to loosen the disc from the hole.

## Friday, 14 October 2016

### CLASS11 PHYSICS CBSE GRAVITATION ONE MARK QUESTIONS

Q1. The mass of moon is nearly 10% of the mass of the earth. What will be the gravitational force of the earth on the moon, in comparison to thegravitational force of the moon on the earth?
Q2. Why does one feel giddy while moving on a merry go round?
Q3. Name two factors which determine whether a planet would have atmosphere or not.
Q4. The force of gravity due to earth on a body is proportional to its mass, then why does a heavy body not fall faster than a lighter body?
Q5. The force of attraction due to a hollow spherical shell of uniform density on a point mass situated inside is zero, so can a body be shielded from gravitational influence?
Q6. The gravitational force between two bodies in 1 N if the distance between
them is doubled, what will be the force between them?
Q7. A body of mass 5 kg is taken to the centre of the earth. What will be its (i) mass (ii) weight there.
Q8. Why is gravitational potential energy negative?
Q9. A satellite revolves close to the surface of a planet. How is its orbital velocity related with escape velocity of that planet.
Q10. Does the escape velocity of a body from the earth depend on (i) mass of the body (ii) direction of projection
Q11. A satellite does not require any fuel to orbit the earth. Why?
Q12. A satellite of small mass burns during its desent and not during ascent.Why?
Q13. Is it possible to place an artificial satellite in an orbit so that it is always
visible over New Delhi?
Q14. If the density of a planet is doubled without any change in its radius,how does ‘g’ change on the planet.
Q15. Why is the weight of a body at the poles more than the weight at the
equator? Explain.
Q16. Why an astronaut in an orbiting space craft is not in zero gravity although
he is in weight lessness?
Q17. Write one important use of (i) geostationary satellite (ii) polar satellite.
Q18. A binary star system consists of two stars A and B which have time periods TA and TB, radius RA and RB and masses mA and mB which of the three quantities are same for the stars. Justify.
Q19. The time period of the satellite of the earth is 5 hr. If the separation
between earth and satellite is increased to 4 times the previous value,
then what will be the new time period of satellite.
Q21. Why does the earth impart the same acceleration to every bodies?
Q22. If suddenly the gravitational force of attraction between earth and satellite

become zero, what would happen to the satellite?

### CLASS11 CBSE PHYSICS ROTATIONAL MOTION ONE MARK QUESTION

1. About which axis a uniform cube will have minimum moment of inertia?
2. State the principle of moments of rotational equilibrium.
3. Find the moment of inertia of a disc of radius R and mass m about an axis in its plane at a distance R/2 from its centre.
4. Can the couple acting on a rigid body produce translator motion?
5. Which component of linear momentum does not contribute to angular momentum?
6. A system is in stable equilibrium. What can we say about its potential energy?
7. Is radius of gyration a constant quantity?
8. Two solid spheres of the same mass are made of metals of different densities. Which of them has a large moment of inertia about the diameter?
9. The moment of inertia of two rotating bodies A and B are IA and IB (IA > IB) and their angular momenta are equal. Which one has a greater kinetic energy?
10. A particle moves on a circular path with decreasing speed. What happens to its angular momentum?
11. What is the value of instantaneous speed of the point of contact during pure rolling?
12. Which physical quantity is conserved when a planet revolves around the sun?
13. What is the value of torque on the planet due to the gravitational force of sun?
14. If no external torque acts on a body, will its angular velocity be constant?
15. Why there are two propellers in a helicopter?

16. A child sits stationary at one end of a long trolley moving uniformly with  speed V on a smooth horizontal floor. If the child gets up and runs about on the trolley in any manner, then what is the effect of the speed of the centre of mass of the (trolley + child) system?

## Thursday, 13 October 2016

### CLASS11 CBSE PHYSICS WORK,ENERGY,POWER ONE MARK QUESTIONS

1. Define the conservative and non conservative forces. Give examples of each.
2. A light body and a heavy body have same linear momentum. Which one has greater K.E? (Ans. : lighter body has more K.E.)
3. The momentum of the body is doubled what % does its K.E change?  [Ans : (300%)]
4. A body is moving along a circular path. How much work is done by the centripetal force?
5. Which spring has greater value of spring constant - a hard spring or a delicate spring?
6. Two bodies stick together after collision. What type of collision is in b/w these two bodies?
7. State the two conditions under which a force does no work?
8. How will the momentum of a body changes if its K.E is doubled?
9. K.E of a body is increased by 300 %. Find the % increase in its momentum? (100%)
10. A light and a heavy body have same K.E. which of the two have more momentum and why? (heavier body)
11. Mountain roads rarely go straight up the slop, but wind up gradually. Why?
12. A truck and a car moving with the same K.E on a straight road. Their engines are simultaneously
switched off which one will stop at a lesser distance?
13. What happens to the P.E of a bubble when it rises in water? (decrease)
14. A body is moving at constant speed over a friction surface. What is the
work done by the weight of the body? (W = 0)
15. Is it necessary that work done in the motion of a body over a closed loop is zero for every force in nature? Why?
16. Define spring constant of a spring?

17. What happens when a sphere collides head on elastically with a sphere of same mass initially at rest?

### CLASS 11 CBSE PHYSICS LAWS OF MOTION ONE MARK QUESTIONS

1. A passenger sitting in a car at next, pusher the car from within. The car doesn’t move, why?
2. Give the magnitude and directions of the net force acting on a rain drop falling with a constantspeed.
3. Why the passengers in a moving car are thrown outwards when it suddenly takes a turn?
4. What is the purpose of using shockers in a car?
5. Why are tyres made of rubber not of steel?
6. Wheels are made circular. Why?
7. A force is required to keep a body in uniform motion in a straight line. Comments.
8. On a rainy day skidding takes place along a curved path. Why?
9. Why does a gun recoils when a bullet is being fired?
10. Why is it difficult to catch a cricket ball than a tennis ball even whenboth are moving with the same velocity?
11. Calculate the impulse necessary to stop a 1500 kg car moving at a speed of 25ms–1.
( –37500 N–S)
12. Lubricants are used between the two parts of a machine. Why?
13. What provides the centripetal force to a car taking a turn on a level road?
14. What is inertial frame of reference?
15. An athlete runs a certain distance before taking a long jump. Why?
16. Action and reaction forces do not balance each other. Why?
17. The wheels of vehicles are provided with mudguards. Why?
18. China wares are wrapped in straw paper before packing?
20. Why is it difficult to walk on a sand?
21. The outer edge of a curved road is generally raised over the inner edge.
Why?
22. Explain why the water doesn’t fall even at the top of the circle when the bucket full of water is upside down rotating in a vertical circle?
23. Why does a speedy motor cyclist bends towards the centre of a circular
path while taking a turn on it?

24. If the net force acting upon the particle is zero show that its linear momentum remains constant?

## Monday, 10 October 2016

### ONE MARK QUESTIONS CLASS 11 PHYSICS CBSE KINEMATICS

KINEMATICS
Q1. Under what condition is the average velocity equal the instantaneous velocity ?
Q2. Draw Position time graph of two objects, A & B moving along a straight line, when their relative velocity is zero.
Q3. Suggest a situation in which an object is accelerated and have constant speed.
Q4. Two balls of different masses are thrown vertically upward with same initial velocity. Maximum heights attained by them are h1 and h2 respectively what is h1/h2 ?
Q5. A car moving with velocity of 50 kmh–1 on a straight road is ahead of a jeep moving with velocity 75 kmh–1. How would the relative velocity be altered if jeep is ahead of car?
Q6. Which of the two-linear velocity or the linear acceleration gives the direction of motion of a body?
Q7. Will the displacement of a particle change on changing the position of origin of the coordinate system?
Q8. If the instantaneous velocity of a particle is zero, will its instantaneous acceleration be necessarily zero.?
Q9. A Projectile is fired with Kinetic energy 1 KJ. If the range is maximum, what is its Kinetic energy, at the highest point ?
Q10. Write an example of zero vector.
Q11. State the essential condition for the addition of vectors.
Q12. What is the maximum number of component into which a vector can be resolved?
Q13. A body projected horizontally moves with the same horizontal velocity although it moves under gravity. Why?
Q14. What is the angle between velocity and acceleration at the highest point of a projectile motion?
Q15. When does (i) height attained by a projectile maximum? (ii) horizontal range is maximum?
Q16. What is the angle between velocity vector and acceleration vector in uniform circular motion?
Q17. A particle is in clockwise uniform circular motion the direction of its acceleration is radially
inward. If sense of rotation or particle is anticlockwise then what is the direction of its
acceleration?
Q18. A train is moving on a straight track with acceleration a. A passenger drops a stone. What is
the acceleration of stone with respect to passenger?
Q19. What is the average value of acceleration vector in uniform circular motion over one cycle?
Q20. Does a vector quantity depends upon frame of reference chosen ?
Q21. What is the angular velocity of the hour hand of a clock?
Q22. What is the source of centripetal acceleration for earth to go round the sun?

### ONE MARK QUESTIONS CLASS11 CBSE PHYSICS UNITS AND MEASUREMENT

Dimensions and Measurement

Q1. A New unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the sun and the earth in terms of the new unit if light takes 8 min and 20 s to cover this distance.
Q2. If x = a + bt + ct2, where x is in metre and in seconds, what is the unit of c ?
Q3. What is the difference between mN, Nm and nm ?
Q4. The radius of atom is of the order of 1Ao & radius of Nucleus is of the order of fermi. How many magnitudes higher is the volume of the atom as compared to the volume of nucleus ?
Q5. How many kg make 1 unified atomic mass unit?
Q6. Name same physical quantities that have same dimension.
Q7. Name the physical quantities that have dimensional formula [ML–1 T–2]
Q8. Give two examples of dimension less variables.
Q9. State the number of significant figures in
(i) 0.007m2 (ii) 2.64 × 1024 kg
(iii) 0.2370 g cm–3 (iv) 0.2300m(v) 86400 (vi) 86400m
Q10. Given relative error in the measurement of length is .02, what is thepercentage error?
Q11. A physical quantity P is related to four observables a, b, c and d as
follows :P = a3b2 / ( cd) The percentage errors of measurement in a, b, c and d are 1%, 3%,4% and 2% respectively. What is the percentage error in the quantity P? What is the value of P calculated using the above relation turns out to be 3.763, to value should you round off the result?
Q12. Name the technique used in locating.
(a) an under water obstacle
(b) position of an aeroplane in space.
Q13. Deduce dimensional formulae of—
(i) Boltzmann’s constant
(ii) mechanical equivalent of heat.

Q14. Give examples of dimensional constants and dimensionless constants.