Description : The negative sign in expression ɛ= -vBL shows that the angle between the direction of L and (v x B) is: a. 90 b. 180 c. 45 d. 0
Last Answer : a. 90
Description : A wire loop is moved parallel to a uniform magnetic field. The induced emf in the loop: a. depends on the shape b. depends on area c. depends on nature of loop d. zero
Last Answer : d. zero
Description : A conductor of length L has current I passing through it, when it is placed parallel to a magnetic field. The force experienced by the conductor will be (a) zero (b) BLI (c) B2LI (d) BLI2
Last Answer : (a) zero
Description : ___________ is not affected by a magnetic field a) Change in magnetic flux b) a moving electron c) a stationary proton d) current flowing in a conductor
Last Answer : c) a stationary proton
Description : In the plane of AC generator coil is parallel to the field, then emf induced in coil is: a. maximum b. minimum c. zero d. intermediate
Last Answer : b. minimum
Description : In the plane of the A.C generator coil is perpendicular to the field, then induced emf in the coil is: a. Maximum b. minimum c. zero d. intermediate value
Description : Work done by a uniform magnetic field in moving a charged particle in a circular path is a) qvB sin θ b) mg sin θ c) zero d) mg cos θ
Last Answer : Zero
Description : The induced emf in a coil depends upon: a. Strength of magnetic field b. Resistance of the coil c. area of the coil d. All of them
Last Answer : d. All of them
Description : An electron moves with a velocity of 2 × 106 ms-1 in the direction of a uniform magnetic field of 0.8 Tesla. The force on electron is a) 8 N b) 2 N c) 4 N d) Zero
Last Answer : d) Zero
Description : A current of 5.8 A flows through a 0.25 m long straight conductor which is kept perpendicular in a region of uniform magnetic field of 3.7 T . The force on conductor is a) 5.4 N b) 2.4 N c) 3.4 N d) 6.4 N
Last Answer : a) 5.4 N
Description : If the motor is overloaded, then the magnitude of ‘back emf’” a. Increases b. Decreases c. Constant d. Becomes zero
Last Answer : Increases
Description : The pole faces of U-shaped magnet in a moving coil galvanometer are made concave to a) decrease the strength of magnetic field b) create a non-uniform magnetic field c) make the magnetic field radial d) All of these
Last Answer : c) make the magnetic field radial
Description : If the magnetic flux density and current are at right angles, then component of force acting on the conductor is A. BIL cosθ B. BIL sinθ C. BIL tanθ D. BL sinθ
Last Answer : BIL sinθ
Description : The left hand rule correlates to (a) current, induced e.m.f. and direction of force on a conductor (b) magnetic field, electric field and direction of force on a conductor (c) self induction, ... and direction of force on a conductor (d) current, magnetic field and direction of force on a conductor
Last Answer : (d) current, magnetic field and direction of force on a conductor
Description : Fleming's left hand rule is used to find (a) direction of magnetic field due to current carrying conductor (b) direction of flux in a solenoid (c) direction of force on a current carrying conductor in a magnetic field (d) polarity of a magnetic pole
Last Answer : (c) direction of force on a current carrying conductor in a magnetic field
Description : Which of the following will produce an induced emf: a. Changing area of coil b. Changing magnetic flux c. changing orientation of coil d. all of them
Last Answer : c. changing orientation of coil
Description : The current flowing in a coil due to induced emf depends upon: a. shape of coil b. resistance of coil c. area of coil d. magnetic flux
Last Answer : a. shape of coil
Description : The induced emf is produced in a circuit due to: a. Initial magnetic flux b. final magnetic flux c. Change of magnetic flux d. constant magnetic flux
Last Answer : d. constant magnetic flux
Description : When a motor is just started, back emf is almost ______: a. Infinite b. zero c. minimum d. maximum
Last Answer : d. maximum
Description : Terminal potential difference of a battery is greater than its emf when a. the internal resistance of battery is infinite b. the internal resistance of battery is zero c. the battery is charged d. the battery is discharged
Last Answer : c. the battery is charged
Description : A magnetic field exists around (a) iron (b) copper (c) aluminium (d) moving charges
Last Answer : (d) moving charges
Description : The induced current can be increased by: a. Using strong magnetic field b. moving loop faster c. Replacing loop by coil d. all of above
Last Answer : d. all of above
Description : A proton and a deuteron have same kinetic energies while moving in a perpendicular magnetic field. The following gives the ratio of radii of their circular paths a) √2 : 1 b) 1: √2 c) 1:4 d) 1:1
Last Answer : b) 1: √2
Description : A permeable substance is one (a) which is a good conductor (6) which is a bad conductor (c) which is a strong magnet (d) through which the magnetic lines of force can pass very easily
Last Answer : (d) through which the magnetic lines of force can pass very easily
Description : An electron and a neutron enter a magnetic field with the same velocity. Ratio of electron to neutron’s acceleration is a) mn me b) √ mn me c) √ me mn d) me
Last Answer : a) mn me
Description : The magnetic field is _________ inside a solenoid a) Zero b) uniform c) non-uniform d) infinite
Last Answer : b) uniform
Description : The greatest induced EMF will occur in a straight wire moving at constant speed through a uniform magnetic field when the angle between the direction of the wire's motion and the direction of the magnetic field is w) 0 degrees x) 30 degrees y) 60 degrees z) 90 degrees
Last Answer : ANSWER: Z -- 90 DEGREES
Description : A particle of charge `q` and velocity v passes undeflected through a space with non-zero electric field E and magnetic field B. The undeflecting condi
Last Answer : A particle of charge `q` and velocity v passes undeflected through a space with non-zero electric field ... D. Both B and E are doubled in magnitude
Description : The resistance of a conductor at absolute zero (OK) is a. zero almost b. infinite almost c. May increase or decrease d. None
Last Answer : zero almost
Description : A proton and an electron both moving with the same velocity v enter into a region of magnetic field directed perpendicular to the velocity of the part
Last Answer : A proton and an electron both moving with the same velocity v enter into a region of magnetic field ... be higher D. their orbital radii will be same
Description : If magnetic field is doubled then magnetic energy density becomes: a. Four times b. Two times c. Three times d. Six times
Last Answer : c. Three times
Description : A solenoid has n turns and length l. If length is reduced to l/2 and turns are doubled then magnetic field B produced by it becomes equal to a) 2B b) 4B c) 1/2 B d) None of these
Last Answer : a) 2B
Description : A proton moves in a uniform magnetic field in a circular path of radius R. If the energy of proton is doubled then the new radius becomes a) R √2 b) 2R c) R 2 d) √2 R
Last Answer : d) √2 R
Description : When an iron piece is placed in a magnetic field (a) the magnetic lines of force will bend away from their usual paths in order to go away from the piece (b) the magnetic lines of force will bend ... to pass through the piece (c) the magnetic field will not be affected (d) the iron piece will break
Last Answer : (b) the magnetic lines of force will bend away from their usual paths in order to pass through the piece
Description : The magnetic flux φB through a plane element of area A⃗ in a uniform magnetic field B⃗⃗ is minimum at a) θ = 900 b) θ = 00 c) θ = 1800 d) None of these
Last Answer : a) θ = 900
Description : If the velocity of charged particle has both perpendicular and parallel components while moving through a magnetic field ,then what is the path follow
Last Answer : If the velocity of charged particle has both perpendicular and parallel components while moving through a ... B. Ellipatical C. Linear D. Helical
Description : The direction of induced EMF can be found with the help of -
Last Answer : Lenz’s Law
Description : The phenomena of induced emf was observed by Faraday and Henry in: a. 1931 b. 1831 c. 1535 d. 1940
Last Answer : a. 1931
Description : The phenomenon of producing emf in the coil due to change of current in the coil itself is called: a. mutual induction b. self-induction c. self-inductance d. mutual inductance
Last Answer : d. mutual inductance
Description : A neon flashlight cell with an emf of 1.5V gives a current of 15A when connected directly to an ammeter of resistance 0.04?. Internal resistance of the cell is a. 0.0004? b. 0.06? c. 0.10? d. 0.13?
Last Answer : b. 0.06?
Description : A particle of mass m is moving along a straight path through the origin of coordinates with a velocity v. The angular momentum of the particle about the origin (a) mv (b) Depends on its distance from origin (c) Is zero (d) Changes from positive to negative as it passes through the origin
Last Answer : Ans:(c)
Description : Forward current through a semi-conductor diode circuit is due to ________ (a) Minority carriers (b) majority carriers (c) holes (d) electrons
Last Answer : (b) majority carriers
Description : If 1 ampere current flows through 2m long conductor the charge flow through it in 1 hour will be a. 3600C b. 7200C c. 1C d. 2C
Last Answer : a. 3600C
Description : A material which is slightly repelled by a magnetic field is known as (a) ferromagnetic material (b) diamagnetic material (c) paramagnetic material (d) conducting material
Last Answer : (b) diamagnetic material
Description : Which of the following is a vector quantity ? (a) Relative permeability (b) Magnetic field intensity (c) Flux density (d) Magnetic potential
Last Answer : (b) Magnetic field intensity
Description : The windings of the electromagnetic are usually called: a. Magnetic coils b. Field coil c. Electric coil d. simple coil
Last Answer : c. Electric coil
Description : In motor a permanent magnet provides: a. Electric field b. electric flux c. magnetic field d. gravitational field
Last Answer : d. gravitational field
Description : A magnetic field acts on a charged particles so as to change its: a. speed b. energy c. direction of motion d. all of these
Last Answer : Only direction of motion will change ...it means velocity will change but speed same
Description : Electric current produces magnetic field was suggested by: a. Faraday b. Lenz c. Ohm d. Oerested
Last Answer : c. Ohm
Description : When a uniform magnetic field B is applied to a current carrying coil, the coil will rotate in such a manner that its plane a) becomes parallel to B b) becomes anti-parallel to B c) makes an angle of 600 with B d) becomes perpendicular to B
Last Answer : d) becomes perpendicular to B