Title Unit No. 8 ELECTROMAGNETISM + INDUCTION ( Youtube Students) By Sir Shahid.pdf ✅

ELECTROMAGNETISM + INDUCTION (UNIT-8) MDCAT www.youtube.com/physicswithshahid Q.1 You push a permanent magnet with its north pole away from you toward a loop of conducting wire in front of you. Before the north pole enters the loop the current in the loop is: (A) Zero (B) Clockwise (C) Counterclockwise (D) To your left Q.2 The core of a transformer is cut into very thin sheets and piled together after getting insulated from each other to reduce: (A) Eddy current losses (B) Copper losses (C) Hysteresis losses (D) Heat losses due to resistance of coils Q.3 The turns ratio of step up transformer is 10: 1. If the current of 20A is passed through its primary coil at 220 volts. The value of voltage in the secondary coil assuming the transformer ideal one is: (A) 22 V (B) 2.2 V (C) 2200 V (D) 220 V Q.4 When the power output in watts equals one half the power input, the efficiency of the transformer becomes (A) 100% (B) 200% (C) 50% (D) Zero Q.5 The graph shows the magnitude B of a uniform magnetic field that is perpendicular to the plane of a conducting loop. Rank the five regions indicated on the graph according to the magnitude of the emf induced in the loop, from least to greatest. (A) 1, 2, 3, 4 (B) 2, 4, 3, 1 (C) 4, 3, 1, 2 (D) 1, 3, 4, 2 Q.6 Which of the following is scalar? (A) Magnetic flux (B) emf (C) Flux density (D) Both A and B Q.7 The working of alternating current generator is based on the principle of (A) LENZS law (B) Faradays law (C) Mutual induction (D) Self inductance Q.8 Lenz’s law is based upon law of conversation of (A) Momentum (B) Charge (C) Energy (D) Mass Q.9 Four particles independently move at the same speed in a direction perpendicular to the same magnetic field. Which particle is deflected the most? (A) A copper ion (B) A helium nucleus (C) An electron (D) A proton Q.10 A beam of electrons enters a region in which there are magnetic and electric fields directed at right angles. It passes straight through without deviation. A second beam of electrons traveling twice as fast as the first is then directed along the same line; how is this second beam deviated? (A) Downwards in the plane of the paper (B) Upwards in the plane of the paper (C) Out of the plane of the paper (D) Into the plane of the paper
ELECTROMAGNETISM + INDUCTION (UNIT-8) MDCAT www.youtube.com/physicswithshahid Q.11 A beam of electron passes undeflected through mutually perpendicular electric field and magnetic field. If the electric field is switched off, and the same magnetic field is maintained, the electrons move (A) In a circular orbit (B) Along a parabolic path (C) Along a straight line (D) In an elliptical orbit Q.12 A beam of electrons is moving with constant velocity in a region having simultaneous perpendicular electric and magnetic fields of strength 20V/m and 0.5T respectively at right angles to the direction of motion of the electrons. Then the velocity of electrons must be. (A) 8 m/s (B) 20 m/s (C) 40 m/s (D) (1/40) m/s Q.13 A uniform magnetic field makes an angle of 30◦ with the z axis. If the magnetic flux through a 1-m2 portion of the xy plane is 5Wb then the magnetic flux through a 2-m2 portion of the same plane is: (A) 2.5Wb (B) 4.3Wb (C) 5Wb (D) 10Wb Q.14 The magnetic force acting on a charged particle of charge -2μC in a magnetic field of 2T acting in y direction, when the particle velocity 100cm/s is... (A) -4μN (B) -8μN (C) 8μN (D) 4μN Q.15 If we doubled all the parameters of the force acting on moving charge and = 900 then magnetic force becomes: (A) Half (B) Double (C) Eight Times (D) Four Times Q.16 The normal to a certain 1-m2 area makes an angle of 60◦ with a uniform magnetic field. The magnetic flux through this area is the same as the flux through a second area that is perpendicular to the field if the second area is: (A) 0.866m2 (B) 1.15m2 (C) 0.5m2 (D) 2m2 Q.17 Which one of the following particles projected perpendicular to a uniform magnetic field with the same velocity will be deflected least? (A) Electron (B) Deutron (C) Proton (D) None of these Q.18 A positively charged particle is moving with an angle θ to a uniform magnetic field. The magnetic force makes the particle to move along (A) An elliptical path (B) A parabolic path (C) A circle (D) Helical path Q.19 A charged particle moves through a magnetic field perpendicular to it. The energy of the particle will (A) Decrease (B) Increase (C) Remains unchanged (D) Become Zero Q.20 Which of the following motion of a charged particle is possible when it enters the magnetic field: (A) circular (B) linear (C) helical (D) all are possible Incoming path of electron Magnetic Field
ELECTROMAGNETISM + INDUCTION (UNIT-8) MDCAT www.youtube.com/physicswithshahid Q.21 The objective of transformer is to (A) Increase value of A.C. (B) Decrease value of A.C. (C) Alter value of A.C. (D) Alter value of D.C. Q.22 Lenz’s law deals with the (A) Magnetic field of emf (B) Direction of emf (C) Both of the magnitude and direction of emf (D) Direction of induced current Q.23 The SI unit of induced emf is (A) Vs / A (B) Tesla (C) Henry (D) Volt Q.24 If the magnetic flux linked with a loop varies at the rate of 1wb/min, the induced emf is (A) 1V (B) 1/60V (C) 60V (D) None of these Q.25 Which of the following is most suitable for the core of an electromagnet? (A) Air (B) Soft iron (C) Steel (D) Cu – Ni alloy Q.26 A coil having number of turns N and cross-sectional area A is rotated in a uniform magnetic field B with an angular velocity . The maximum value of the emf induced in it is (A) NBA ω (B) NBA (C) 2 NBA ω (D) NBA 2 Q.27 A step-up transformer is used on a 120 V line to provide a potential difference of 2400 V. If the primary coil has 75 turns, the number of turns in the secondary coil are (A) 1500 (B) 1200 (C) 150 (D) 1575 Q.28 An ideal step down transformer is connected to main supply of 240 V. It is desired to operate at 12 V, 300 W lamp. Find the current in primary. (A) 0.125 A (B) 1.25 × 10–2 (C) 1.25 × 10–1 A (D) 1.25 A Q.29 The number of turns in primary and secondary windings of a transformer are as shown in following figure. What must be the voltage across secondary? (A) 22 V (B) 220 V (C) 2200 V (D) Zero Q.30 An electron moves in circular orbit with uniform speed v. It produces a magnetic field B at the centre of the circle. the radius of the circle is proportional to ... (A) √ B v (B) B v (C) √ v B (D) v B Secondary N 10 S = 220V N 1000 P = Primary