Physics-DPP1-7.Electromagnetic Induction & Alternating current

PHYSICS Topic: E. M. I and A/C Date: 1. Flux  (in weber) in a closed circuit of resistance 10 ohm varies with time t (in sec) according to the equation:  = 6t2 – 5t + 1. What is the magnitude of the induced current at t = 0.25 sec? (a) 1.2 A (b) 0.8 A (c) 0.6 A (d) 0.2 A 2. A magnet NS is suspended from a spring and while it oscillates the magnet moves in and out of the coil C. If the coil is now connected to a galvanometer G as shown in the figure, then as the magnet oscillates, G shows: (a) No deflection (b) Deflection on one side (c) Deflection to the leftand right with eonstant amplitude (d) Deflection to the left and right but amplitude steadily decreases 3. An electric potential difference will be induced between the ends of the conductor shown in the figure when the conductor moves in the direction: (a) P (b) Q (c) L (d) M 4. A conducting square loop of side L and resistance R moves in its plane with a uniform velocity v perpendicular to one of its sides. A magnetic induction B, constant in time and space, pointing perpendicular and into the plane of theloop exists everywhere. The current induced in the loop is: (a) Blv clockwise R (b) Blv anticlockwise R (c) 2Blv anticlockwise R (d) zero 5. Two different loops are concentric and lie in the same plane. The current in the outer loop is clockwise and increases with time. The induced current in the inner loop then is: (a) clockwise (b) zero (c) counterclockwise (d) in a direction that depends on the ratio of the loop radii PHYSICS Topic: E. M. I and A/C Date: 6. Aconductor rod AB moves parallel to x-axis in a uniform magnetic field, pointing in the positive x-direction. The end A of th rod gets: (a) Positively charged (b) negatively charged (c) neutral (d) first positively charged and then negatively charged 7. Figure shows a solenoid connected with a resistance R, a bulb B and a source of e.m.f. The resistance R is adjusted so that when the key K is closed, the bulb just glows. Then the switch K is suddenly opened. Then bulb B will: (a) remain as before (b) go out (c) glow very brightly (d) none of these 8. The north pole of a long horizontal bar magnet is being brought closer to a vertical conducting plane along the perpendicular direction. The direction of the induced current in the conducting plane will be: (a) horizontal (b) vertical (c) clockwise (d) anticlockwise 9. If the angular speed of rotation of an armature of alternating current generator is doubled, then the induced electromotive force will be: (a) twice (b) four times (c) no change (d) half 10. An aeroplane is moving towards north horizontally with a speed of 200 m s–1 at a place where the verticle component of earth’s magnetic field is 0.5 × 10–4 tesla. Then the induced e.m.f. set up between the tips of the wings of the plane if they are 10 m apart is: (a) 0.1 volt (b) 0.01 volt (c) 10 volt (d) 1 volt *****End of Paper***** PHYSICS Topic: E. M. I and A/C Answer key Date: 1.(d) 2.(d) 3. (d) 4. (d) 5. (c) 6. (b) 7. (c) 8. (b) 9. (a) 10. (a)

Comments

Post a Comment

Popular posts from this blog

Planning to start your own coaching institute for JEE, NEET, CBSE or Foundation? Here's why not to waste time in developing study material from scratch. Instead use the readymade study material to stay focused on quality of teaching as quality of teaching is the primary job in coaching profession while study material is secondary one. Quality of teaching determines results of your coaching that decides success & future of your coaching while good quality study material is merely a necessary teaching aid that supplements your teaching (video in Hindi)

Image
Read more

Physics-30.24-Physics-Solids and Semiconductors

UNIT 24 - SOLIDS AND SEMICONDUCTORS 1. SOLID STATE ELECTRONICS (SEMICONDUCTORS) (A) Energy bands in solids: (i) In solids, the group of closely lying energy levels is known as energy band. (ii) In solids the energy bands are analogous to energy levels in an atom. (iii) In solids the atoms are arranged very close to each other. In these atoms there are discrete energy levels of electrons. For the formation of crystal these atoms come close together, then due to nucleus-nucleus, electron-electron and electron-nucleus interactions the discrete energy levels of atom distort and consequently each energy level spits into a large number of closely lying energy levels. (iv) The number of split energy levels is proportional to the number of atoms interacting with each other. If two atoms interact then each energy level splits into two out of which one will be somewhat above and another will be somewhat below the main energy level. In solids the number of atoms is very large ( 1023). Hence eac...
Read more

Physics-31.Rotational Mechanics

5.1 DEFINITION OF CENTRE OF MASS Centre of mass: Every physical system has associated with it a certain point whose motion characterizes the motion of the whole system. When the system moves under some external forces than this point moves as if the entire mass of the system is concentrated at this point and also the external force is applied at his point of translational motion. This point is called the centre of mass of the system. Centre of mass of system of n point masses or n particles is that point about which moment of mass of the system is zero, it means that if about a particular origin the moment of mass of system of n point masses is zero, then that particular origin is the centre of mass of the system. The concept of centre of mass is a pure mathematical concept. If there are n particles having mass m1, m2 ….m n and are placed in space (x1, y1, z1), (x2, y2, z2) ……….(x n, y n, z n) then centre of mass of system is defined as (X, Y, Z) where = Y = and Z = where...
Read more