If magnetic field is doubled then magnetic energy density becomes:
a. Four times b. Two times c. Three times d. Six times

1 Answer

Answer :

c. Three times

Related questions

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 : 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 : If the distance between the two charge bodies is halved, the force between them becomes: (a) Half (b) Four time (c) One fourth (d) Doubled

Last Answer : (c) One fourth

Description : A wire of uniform area of cross-section A length L and resistance R is cut into two parts. Resistivity of each part a. remains the same b. is doubled c. is halved d. becomes zero

Last Answer : a. remains the same

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

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 : If a material object moves with the speed of light ‘c’ its mass becomes a) equal to its rest mass b) Four times of its rest mass c) Double of its rest mass d) Infinite

Last Answer : d) Infinite

Description : When the velocity of a body is doubled, its 1. acceleration is doubled 2. momentum is doubled 3. kinetic energy becomes four times 4. potential energy is doubled Which of the above is/are correct? (a) 2 only (b) 2 and 3 (c) 3 only (d) 2 and 4

Last Answer : Ans:(b)

Description : If velocity of a conductor moving through a magnetic field ‘B’ is made zero, then Motional emf will be: a. –VBL b. –V/BL c. – BL/V d. zero

Last Answer : a. –VBL

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 : Which of the following quantities change when a proton moves at right angles to a magnetic field? a) Momentum b) Energy c) Speed d) All of these

Last Answer : a) Momentum

Description : Which of the following does not equal the unit of magnetic flux density? a) 1 Wbm-2 b) 1 NA-1m -1 c) Both (a) and (b) d) 1 Wbm-1

Last Answer : d) 1 Wbm-1

Description : Current carried by each of the two long parallel conductors is doubled. If their separation is also doubled , force between them is

Last Answer : Increase two fold

Description : If the Earth's magnetic field lines pass through the Hall probe in opposite direction, then the change in reading of voltmeter is A. thrice the Earth's magnetic flux density B. four times the Earth ... C. five times the Earth's magnetic flux density D. twice the Earth's magnetic flux density

Last Answer : twice the Earth's magnetic flux density

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 : 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 : 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 : 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 : 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 : A magnetic field exists around (a) iron (b) copper (c) aluminium (d) moving charges

Last Answer : (d) moving charges

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 : 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 : 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 : In motor a permanent magnet provides: a. Electric field b. electric flux c. magnetic field d. gravitational field

Last Answer : d. gravitational field

Description : Electric current produces magnetic field was suggested by: a. Faraday b. Lenz c. Ohm d. Oerested

Last Answer : c. Ohm

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 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 : 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 : An α particle moves perpendicular to a constant magnetic field of strength 1.2 T in a circular path of radius 0.7 m. The speed of α particle in ms-1 is ______________ a) 2.7 × 107 b) 2.6 × 107 c) 3.2 × 107 d) 2.0 × 107

Last Answer : a) 2.7 × 107

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 : The magnetic field is _________ inside a solenoid a) Zero b) uniform c) non-uniform d) infinite

Last Answer : b) uniform

Description : A proton and a α particle enter a region having a perpendicular uniform magnetic field. The ratio of time period of proton (τp) to time period of α particle (τα) is a) 1:4 b) 4:1 c) 2:1 d) 1:2

Last Answer : d) 1:2

Description : A proton having mass m and charge q is projected into a region having a perpendicular magnetic field. The angle of deviation of proton when it comes out of the region with mv √2 qB ⁄ is a) π/3 b) π/4 c) π/6 d) 2 π/3

Last Answer : b) π/4

Description : ___________ remain undeflected in a magnetic field a) β particles b) α particles c) γ rays d) Proton beams

Last Answer : c) γ rays

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 : A magnetic screw placed in a non-uniform magnetic field experiences a) force and torque b) only torque c) only force d) None of these

Last Answer : a) force and torque

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 : 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 : ___________ 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 : 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 : When the field is strong, the lines of force are: (a) Closer (b) Parallel (c) Farther (d) All of above 45. The electric lines of force determine the strength of an: (a) Gravitational field (b) Constant field (c) Magnetic field (d) Electric field

Last Answer : d) Electric field

Description : The space around the charge within which other charges are influenced by it is called: (a) Electric field (b) Magnetic field (c) Electric flux (d) Electric intensity

Last Answer : a) Electric field

Description : Tesla is a unit of (a) field strength (b) inductance (c) flux density (d) flux

Last Answer : (c) flux density

Description : A circular flexible loop of wire of radius r carrying a current I is placed in a uniform magnetic field B . If B is doubled, then tension in the loop

Last Answer : A circular flexible loop of wire of radius r carrying a current I is placed in a uniform magnetic field ... is doubled C. is halved D. becomes 4 times

Description : In a ferromagnetic material the state of flux density is as follows when external magnetic field is applied to it. (A) Increased (B) Decreased (C) Remains unchanged (D) Becomes zero

Last Answer : (C) Remains unchanged

Description : A three dimensional image is obtained by a)Electron microscope b) Scanning electron microscope c) Magnetic imaging d)None of these

Last Answer : b) Scanning electron microscope

Description : Energy stored per unit volume inside the solenoid is called: a. Energy density b. Charge Density c. Mass density d. Volume charge density

Last Answer : energy density is correct

Description : The energy density of an inductor is: a. B 2 / 2 μ2 b. B/ 2 μ c. B/ 2 μ2 d. B 2 / 2 μ

Last Answer : c. B/ 2 μ2

Description : The termcritical angle describes a. the point at which light is refracted b. the point at which light becomes invisible c. the point at which light has gone from the refractive mode to the reflective mode d. the point at which light has crossed the boundary layers from one index to another

Last Answer : c. the point at which light has gone from the refractive mode to the reflective mode