Page 1 :
3 MAGNETISM AND MAGNETIC EFFECT OF ELECTRIC, CURRENT, Two Marks and Three marks, I) Book Back Question, , 1. What is meant by magnetic induction?, 1 a) Define magnetic field., 2. Define magnetic flux., 3. Define magnetic dipole moment., 4. State Coulomb’s inverse square law. (In magnetism), 5. What is magnetic susceptibility?, 6. State Biot-Savart’s law., 7. What is magnetic permeability?, 8. State Ampere’s circuital law., 9. Compare dia, para and ferro magnetism., 10. What is meant by hysteresis?, 11. Define magnetic declination (D) and inclination (I)., 12. What is resonance condition in cyclotron?, 13. Define ampere., 14. State Fleming’s Left Hand Rule., 15. Is an ammeter connected in series or parallel in a circuit? Why?, 16. Explain the concept of velocity selector?, 17. Why is the path of a charged particle not a circle, when its velocity is not perpendicular to the, magnetic field?, 18. Give the properties of dia, para and ferro magnetic materials, 19. What happen to the domains in ferro magnetic materials in the presence of external magnetic, field?, 20. How is galvanometer converted into an ammeter and a voltmeter?, , II) Book Interior Questions, , 1. Define Horizontal component of Earth’s magnetic field (BH)., 2. What is Aurora Borealis and Aurora Australis?, 3. State Curie’s law., 4. Write the properties of magnet., 5. Write a short note on pole strength., 6.Why a freely suspended bar magnet in our laboratory experiences only torque (rotational, motion ) but not any translator motion even though Earth has non-uniform magnetic field?, 7. Suppose we keep a freely suspended bar magnet in a non-uniform magnetic field. What will, happen?, 8. What is Meissner effect?, 9. What is magnetometer surveying?, 10. Define Remanence., 11. Define coercivity., 12. State Right hand thumb rule., 13. State Maxwell’s right hand cork screw rule., A.SENTHIL KUMAR PG.ASST GBHSS, MECHERI, METTUR TK, SALEM DT 94425 62850, , Page 1

Page 2 :
14. State Tangent law., 15. Write a short not on MRI scans., 16. Write down the difference between electric field and magnetic field on the basis of, Coulomb’s law and Biot-Savart law. And also write down the similarities., 17. Write a short note on neutron cancer therapy., 18. Define figure of a merit of a galvanometer?, 19. What is current sensitivity of a galvanometer? And what factors it is depend on?, 20. What is voltage sensitivity of the galvanometer?, 21. Increasing the current sensitivity of the Galvanometer does not necessarily increase the, voltage sensitivity. Why?, 22. What is the importance of radial magnetic field in moving coil galvanometer?, 23. State magnetic force and Lorentz force., 24. Define Bohr magneton., 25. What is Gyro – Magnetic ratio?, 26. What is Geo magnetism or terrestrial magnetism?, 27. What are the elements of Earth’s Magnetic field?, 28. What is geographic meridian and Geographic equator?, 29. What is magnetic meridian and Magnetic equator?, ) of the magnet?, 30. What is polestrength, 31. State the magnets types., 32. Define magnetic flux density., 33. Define Curie temperature and state Curie – Weiss law., 34. What is Hysteresis loss?, 35. What is Hard and soft magnetic materials?, 36. State right hand thumb rule. (Magnetic dipole moment), 37. State the end rule., 38. Write a short note on Solenoid., 39. What is relative permeability?, 40. What is intensity of magnetization?, 41. Write down the types of magnetic fields, 42. What is the importance of the radial magnetic field in moving coil galvanometer?, , III) Conceptual Questions, , 1. In what way is an electric field different from magnetic field with respect to the presence of, electric charge?, 2. A charged particle is released from rest in a region of steady and uniform electric and, magnetic fields, which are parallel to each other, what will be the nature of the path followed by, the charged particle?, 3. An electron travelling from west to east enters a chamber having a uniform electrostatic field, in a north to south direction. Specify the direction in which a uniform magnetic field should be, set up to prevent the electron deflecting from its straight line path., 4. Why do the two long parallel conductors carrying current exert force on each other?, 5. Why do two straight parallel metallic wires carrying current in the opposite direction repel, each other?, 6. Why should a solenoid tend to contract, when a current passes through it?, A.SENTHIL KUMAR PG.ASST GBHSS, MECHERI, METTUR TK, SALEM DT 94425 62850, , Page 2

Page 3 :
7. Explain, why earth’s magnetic field does not affect the working of a moving coil, galvanometer., 8. When an ammeter is put in a circuit, does it read slightly less or more than the actual current, in the original circuit? Explain., 9. Why an ammeter should have as low a resistance as possible? Explain., 10. A good quality voltmeter should have a large resistance. Explain., 11. When a voltmeter is put across a part of the circuit, does it reads slightly less or more than, original potential drop across that part? Explain., 12. What are the primary functions of electric field and magnetic field in a cyclotron?, 13. Why does not a charged particle moving at right angle to the direction of an electric field, follow a circular path?, 14. Why does a charged particle at right angle to the direction of a magnetic field follow a, circular path?, 15. An electron and a proton are freely situated in an electric field. Will the electric force on, them be equal? Will their acceleration be equal? Justify your answer., 16. Describe qualitatively, the path of a charged particle in a uniform magnetic field with initial, velocity,, a) parallel to the field, b) perpendicular to the field, c) at an arbitrary angle with the field direction., Solution,, 17. An electric charge moving in a direction making an angle (≠ 90° ) with the direction of, magnetic field follows a helical path. Why?, 18. You are given two identical looking bars A and B. One of these is a bar magnet and other an, ordinary piece of iron. Given an experiment to identify, which one of the two is a bar magnet?, You are not to use any additional materials for the experiment., 19. A steel wire of length has a magnetic moment M. It is then bent into a semicircular arc,, what is the new magnetic moment?, 20. Must every magnetic field configuration have a north pole and south pole? What about the, field due to a toroid?, 21. Magnetic field arises due to charges in motion. Can a system have magnetic moment, even, though its net charge is zero?, 22. If magnetic monopoles existed, how would Gauss’s law of magnetism be modified?, 23. A magnetic needle is placed on a cork floating on a still lake in the northern hemisphere., Does this needle together with the cork move towards the north of the lake?, 24. Give three advantages of a moving coil galvanometer over the tangent galvanometer., 25. Why is diamagnetism independent of temperature?, 26. Why do we use steel or alnico for making permanent magnets?, , NUMERICAL PROBLEMS BOOK INTERIOR, , 1. The Horizontal component and vertical component of Earth’s magnetic field at a place are, 0.15 G and 0.26 G respectively. Calculate the angle of dip and resultant magnetic field. ( G, for gauss, cgs unit for magnetic field 1 = 10, ), A.SENTHIL KUMAR PG.ASST GBHSS, MECHERI, METTUR TK, SALEM DT 94425 62850, , Page 3

Page 4 :
2. Let the magnetic moment of a bar magnet be, whose magnetic length is = 2 and pole, strength is qm. Compute the magnetic moment of the bar magnet when it is cut into pieces, a) along its length, b) perpendicular to its length., 3. Compute the magnetic length of a uniform bar magnet if the geometrical length of the magnet, is 12 cm. Mark the positions of magnetic pole points., 4. The repulsive force between two magnetic poles in air is 9 × 10, . If the two poles are, equal in strength and are separated by a distance of 10 cm, calculate the pole strength of each, pole., 5. A short bar magnet has a magnetic moment of 0.5 J T -1. Calculate magnitude and direction of, the magnetic field produced by the bar magnet which is kept at a distance of 0.1 m from the, centre of the bar magnet along, a) axial line of the bar magnet., b) normal bisector of the bar magnet., 6. Calculate the magnetic flux coming out from closed surface containing magnetic dipole (say,, a bar magnet) as shown in figure., , 7. Compute the intensity of magnetization of the bar magnet whose mass, magnetic moment and, density are 200 g, 2 A m2 and 8 g cm-3, respectively., , 8. Using the relation =, +, , show that, =, − 1., 9. Two materials X and Y are magnetized whose values of intensity of magnetization are, 500 A m-1 and 2000 A m-1 respectively. If the magnetizing field is 1000 A m -1, then which one, among these materials can be easily magnetized?, 10. The following figures shows the variation of intensity of magnetization with the applied, magnetic field intensity for three magnetic materials X, Y and Z., , A.SENTHIL KUMAR PG.ASST GBHSS, MECHERI, METTUR TK, SALEM DT 94425 62850, , Page 4

Page 5 :
11. What is the magnetic field at the centre of the loop shown in figure?, , 12. A coil of a tangent galvanometer of diameter 0.24 m has 100 turns. If the horizontal, component of Earth’s magnetic field is 25 × 10, then, calculate the current which gives a, °, deflection of 60 ., 13. Compute the magnitude of the magnetic field of a long, straight wire carrying a current of 1, A at distance of 1 m from it. Compare it with Earth’s magnetic field., 14. Calculate the magnetic field inside a solenoid, when, a) length of the solenoid becomes twice with fixed number of turns, b) both the length of the solenoid and number of turns are doubled, c) the number of turns becomes twice for the fixed length of the solenoid, compare the results, 15. Compute the workdone and power delivered by the Lorentz force on the particle of charge q, moving with velocity of the charged particle and also interpret the result., 16. A particle of charge q moves with velocity along positive y direction in a magnetic field, , . Compute the Lorentz force experienced by the particle, a) When magnetic field along positive y direction, b) When magnetic field points in positive z direction, c) When magnet field is in zy plane and making an angle with velocity of the particle. Mark, the direction of magnetic force in each case., 17. An electron moving perpendicular to a uniform magnetic field 0.500 T undergoes circular, motion of radius 2.50 mm. What is the speed of electron?, 18. A proton moves in a uniform magnetic field of strength 0.500 T magnetic field is directed, along the x axis. At initial time, t = 0 s, the proton has velocity, = 1.95 × 10 ̂ + 2.00 × 10, find, a) At initial time, What is the acceleration of the proton., b) Is the path circular or helical? If helical, calculate the radius of helical trajectory and also, calculate the pitch of the helix., Note ( Pitch of the helix is the distance travelled along the helix axis per revolution), 19. Let E be the electric field of magnitude 6.0 × 10, and B be the magnetic field of, magnitude 0.83 T. Suppose an electron is accelerated with a potential of 200 V, will it show, zero deflection? If not, at what potential will it show zero deflection., 21. Suppose a cyclotron is operated to accelerate protons with a magnetic field of strength 1 T., Calculate the frequency in which the electric field between two Dees could be reversed., 22. A metallic rod of linear density is 0.25 kg m-1 is lying horizontally on a smooth inclined, plane which makes an angle of 45° with the horizontal. The rod is not allowed to slide down by, A.SENTHIL KUMAR PG.ASST GBHSS, MECHERI, METTUR TK, SALEM DT 94425 62850, , Page 5

Page 6 :
flowing a current through it when a magnetic field of strength 0.25 T is acting on it in the vertical, direction. Calculate the electric current flowing in the rod to keep it stationary., 23. The coil of a moving coil galvanometer has 5 turns and each turn has an effective area of, 2 × 10, . It is suspended in a magnetic field whose strength is 4 × 10, . If the, torsional constant K of the suspension fibre is 4 × 10, ., a) Find its current sensitivity in division per micro ampere., b) Calculate the voltage sensitivity of the galvanometer for it to have full scale deflection of 50, divisions for 25 mV., c) Compare the resistance of the galvanometer., 24. The resistance of a moving coil galvanometer is made twice its original value in order to, increase current sensitivity by 50 %. Find the percentage change in voltage sensitivity., , NUMERICAL PROBLEMS BOOK BACK, , 1. A bar magnet having a magnetic moment, is cut into four pieces i.e., first cut into two, pieces along the axis of the magnet and each piece is further cut along the axis two pieces., Compute the magnetic moment of each piece., 2. A conductor of linear mass density 0.2 g m-1 suspended by two flexible wires as shown in, figure. Suppose the tension in the supporting wires is zero when it is kept inside the magnetic, field of 1 T whose direction is into the page. Compute the current inside the conductor and also, the direction of the current. Assume g = 10 m s -2., , 3. A circular coil with cross sectional area 0.1 cm2 is kept in a uniform magnetic field of, strength 0.2 T. If the current passing in the coil is 3 A and plane of the loop is perpendicular to, the direction of magnetic field. Calculate, A) total torque on the coil., b) total force on the coil., c) average force on each electron in the coil due to the magnetic field. (The free electron density, for the material of the wire is 1028 m-3)., 4. A bar magnet is placed in a uniform magnetic field whose strength is 0.8 T. If the bar magnet, is oriented at an angle 30° with the external field experiences a torque of 0.2 N m. Calculate, a) the magnetic moment of the magnet, b) the work done by the magnetic field in moving it from most stable configuration to the most, unstable configuration and also compute the work done by the applied magnetic field in this case, A.SENTHIL KUMAR PG.ASST GBHSS, MECHERI, METTUR TK, SALEM DT 94425 62850, , Page 6

Page 7 :
5. A non conducting sphere has a mass of 100 g and radius 20 cm. A flat compact coil of wire, with turns 5 is wrapped tightly around it with each turns concentric with the sphere. This sphere, is placed on an inclined plane such that plane of coil is parallel to the inclined plane. A uniform, magnetic field of 0.5 T exists in the region in vertically upward direction. Compute the current I, required to rest the sphere in equilibrium., , 6. Calculate the magnetic field at the centre of a square loop which carries a current of 1.5 A,, length of each side being 50 cm., , FIVE MARK BOOKBACK QUESTIONS, 1. Discuss the Earth’s magnetic field in detail., 2. Deduce the relation for the magnetic field at a point due to an infinitely long straight, conductor carrying current., 3. Obtain a relation for the magnetic field at a point along the axis of a circular coil carrying, current., 4. Compute the torque experienced by a magnetic needle in a uniform magnetic field., 5. Calculate the magnetic field at a point on the axial line of a bar magnet., 6. Obtain the magnetic field at a point on the equatorial line of a bar magnet., 7. Find the magnetic field due to a long straight conductor using Ampere’s circuital law., 8. Discuss the working of cyclotron (high energy oscillator) in detail., 9. What is tangent law? Discuss in detail., 9 a. Explain in detail the principle, construction and theory of a tangent galvanometer., 10. Derive an expression for the torque on a current carrying coil in a magnetic field., 11 a)Discuss the conversion of galvanometer into an ammeter., 11 b)Discuss the conversion of galvanometer into an ammeter., 12. Calculate the magnetic field inside and outside of the long solenoid using Ampere’s circuital, law., 13. Derive the expression for the force between two parallel, current-carrying conductors., 14. Give an account of magnetic Lorentz force., 15. Compare the properties of soft and hard ferromagnetic materials., 16. Derive the Expression for the force on a current-carrying conductor in a magnetic field., A.SENTHIL KUMAR PG.ASST GBHSS, MECHERI, METTUR TK, SALEM DT 94425 62850, , Page 7

Page 8 :
ADDITIONAL FIVE MARK QUESTIONS, 1., 2., 3., 4., 5., , Write a short note on Toroid. Discuss the value of magnetic fields at various points., Explain the device the Moving Coil Galvanometer (MCG)., Derive an expression for potential energy of a bar magnet in a uniform magnetic field ., What is Hysteresis loop? Write down the application of hysteresis loop., Explain, Magnetic dipole moment of revolving electron., , A.SENTHIL KUMAR PG.ASST GBHSS, MECHERI, METTUR TK, SALEM DT 94425 62850, , Page 8