# Magnetic Effect of Current Important Questions ### Magnetic effect of current and Magnetism objective type questions with answers:

Ques. A moving coil sensitive galvanometer gives at once much more deflection. To control its speed of deflection
(a) A high resistance is to be connected across its terminals
(b) A magnet should be placed near the coil
(c) A small copper wire should be connected across its terminals
(d) The body of galvanometer should be earthed

Ans. (b)

Ques. Two straight horizontal parallel wires are carrying the same current in the same direction, d is the distance between the wires. You are provided with a small freely suspended magnetic needle. At which of the following positions will the orientation of the needle be independent of the magnitude of the current in the wires
(a) At a distance d/2 from any of the wires
(b) At a distance d/2 from any of the wires in the horizontal plane
(c) Anywhere on the circumference of a vertical circle of radius d and centre halfway between the wires
(d) At points halfway between the wires in the horizontal plane

Ans. (d)

Ques. Two parallel beams of electrons moving in the same direction produce a mutual force
(a) Of attraction in plane of paper
(b) Of repulsion in plane of paper
(c) Upwards perpendicular to plane of paper
(d) Downwards perpendicular to plane of paper

Ans. (b)

Ques. At a distance of 10 cm from a long straight wire carrying current, the magnetic field is 0.04 T. At the distance of 40 cm, the magnetic field will be
(a) 0.01 T
(b) 0.02 T
(c) 0.08 T
(d) 0.16 T

Ans. (a)

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Ques. The sensitiveness of a moving coil galvanometer can be increased by decreasing
(a) The number of turns in the coil
(b) The area of the coil
(c) The magnetic field
(d) The couple per unit twist of the suspension

Ans. (d)

Ques. The magnetic field at a distance r from a long wire carrying current i is 0.4 Tesla. The magnetic field at a distance 2r is
(a) 0.2 Tesla
(b) 0.8 Tesla
(c) 0.1 Tesla
(d) 1.6 Tesla

Ans. (a)

Ques. A stream of electrons is projected horizontally to the right. A straight conductor carrying a current is supported parallel to electron stream and above it. If the current in the conductor is from left to right then what will be the effect on electron stream
(a) The electron stream will be pulled upward
(b) The electron stream will be pulled downward
(c) The electron stream will be retarded
(d) The electron beam will be speeded up towards the right

Ans. (b)

Ques. A current flows in a conductor from east to west. The direction of the magnetic field at a points above the conductor is ..
(a) Towards north
(b) Towards south
(c) Towards east
(d) Towards west

Ans. (a)

Ques. One proton beam enters a magnetic field of 10–4T normally, Specific charge = 1011 C/kg velocity = 107 m/s. What is the radius of the circle described by it
(a) 0.1 m
(b) 1 m
(c) 10 m
(d) 100 m

Ans. (b)

Ques. A wire carrying current I and other carrying 2I in the same direction produces a magnetic field B at the mid point. What will be the field when 2I wire is switched off
(a) B / 2
(b) 2B
(c) B
(d) 4B

Ans. (c)

Ques. A small cylindrical soft iron piece is kept in a galvanometer so that
(a) A radial uniform magnetic field is produced
(b) A uniform magnetic field is produced
(c) There is a steady deflection of the coil
(d) All of these

Ans. (d)

Ques. A uniform magnetic field acts at right angles to the direction of motion of electrons. As a result, the electron moves in a circular path of  radius 2 cm. If the speed of the electrons is doubled, then the radius of the circular path will be
(a) 2.0 cm
(b) 0.5 cm
(c) 4.0 cm
(d) 1.0 cm

Ans. (c)

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Ques. A charged particle moving in a magnetic field experiences a resultant force
(a) In the direction of field
(b) In the direction opposite to that field
(c) In the direction perpendicular to both the field and its velocity
(d) None of these

Ans. (c)

Ques. A charge + Q is moving upwards vertically. It enters a magnetic field directed to the north. The force on the charge will be towards
(a) North
(b) South
(c) East
(d) West

Ans. (d)

Ques. A beam of electrons and protons move parallel to each other in the same direction, then they
(a) Attract each other
(b) Repel each other
(c) No relation
(d) Neither attract nor repel

Ans. (a)

Ques. A charged particle enters a magnetic field H with its initial velocity making an angle of 45o with H. The path of the particle will be
(a) A straight line
(b) A circle
(c) An ellipse
(d) A helix

Ans. (d)

Ques. “On flowing current in a conducting wire the magnetic field produces around it.” It is a law of
(a) Lenz
(b) Ampere
(c) Ohm
(d) Maxwell

Ans. (b)

Ques. An electron moving towards the east enters a magnetic field directed towards the north. The force on the electron will be directed
(a) Vertically upward
(b) Vertically downward
(c) Towards the west
(d) Towards the south

Ans. (b)

Ques. Electromagnetism was discovered by __
(a) SC Bose
(b) Newton
(d) Edison

Ans. (c)

Ques. By increasing the number of turns in the coils the strength of the magnetic field
(a) Decreases
(b) Increases
(c) First decreases then increases
(d) Remains unchanged

Ans. (b)

Ques. A charged particle is released from rest in a region of steady uniform electric and magnetic fields which are parallel to each other the particle will move in a
(a) Straight line
(b) Circle
(c) Helix
(d) Cycloid

Ans. (a)

Ques. An electron moving with a uniform velocity along the positive x-direction enters a magnetic field directed along the positive y-direction. The force on the electron is directed along
(a) Positive y-direction
(b) Negative y-direction
(c) Positive z-direction
(d) Negative z-direction

Ans. (d)

Ques. Which of the following statements is not true regarding electromagnets?
(a) They do not lose magnetism when electric current is switched off
(b) They can be made very strong to lift heavy objects
(c) They are  used to separate magnetic material from junk
(d) They attract pieces of iron

Ans. (a)

Ques. If two streams of protons move parallel to each other in the same direction, then they
(a) Do not exert any force on each other
(b) Repel each other
(c) Attract each other
(d) Get rotated to be perpendicular to each other

Ans. (b)

Ques. If a long hollow copper pipe carries a direct current, the magnetic field associated with the current will be
(a) Only inside the pipe
(b) Only outside the pipe
(c) Neither inside nor outside the pipe
(d) Both inside and outside the pipe

Ans. (b)

#### Richa Bhardwaj

Richa (B. Tech) has keen interest in Science and loves to teach students about it through lectures and assignments. She always try to use simple language and sentences while writing to make sure learner understands everything properly.