CBSE Class 10 Science Magnetic Effects of Electric Current MCQs Set F

Question: The magnetic field inside a long straight solenoid-carrying current
a) is zero.
b) decreases as we move towards its end.
c) increases as we move towards its end.
d) is the same at all points.
Answer: d

Question: Which of the following property of a proton can change while it enters freely in a magnetic field? (There may be more than one correct Answer: .)
a) mass
b) speed
c) velocity
d) momentum
Answer: b

Question: Two organs where magnetic field is produced are
a) Heart and lungs
b) Heart and brain
c) Brain and lungs
d) Heart and Liver
Answer: b

Question: If a rectangular copper wired coil is rotated in magnetic field, in how many revolutions, the direction of induced current will be change?
a) one
b) two
c) half
d) three
Answer: c

Question: When the speed of rotation of coil is doubled, the frequency of current will be
a) same
b) doubled
c) half
d) quadrupled times
Answer: b

Question: Choose the incorrect statement from the following regarding magnetic lines of force
a) The direction of magnetic field at a point is taken to be the direction in which the north pole of a magnetic compass needle will point
b) Magnetic field lines are closed curves
c) If magnetic field lines are parallel and equidistant, they represent zero field strength
d) Relative strength of magnetic field is shown by the degree of closeness of the field lines
Answer: c

Question: For the current in a long straight solenoid N- and S-poles are created at the two ends. Among the following statements, the incorrect statement is
a) The field lines inside the solenoid are in the form of straight lines which indicates that the magnetic field is the same at all points inside the solenoid
b) The strong magnetic field produced inside the solenoid can be used to magnetise a piece of magnetic material like soft iron core, when placed inside the coil
c) The pattern of magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet
d) The N- and S-poles exchange positions when the direction of current through the solenoid is reversed
Answer: c

Question: A circular loop placed in a plane perpendicular to the plane of paper carries a current when the key is ON. The current as seen from points A and B (in the plane of paper and on the axis of the coil) is anti clockwise and clockwise respectively. The magnetic field lines point from B to A. The N-pole of the resultant magnet is on the face close to
a) A
b) B
c) A if the current is small, and B if the current is large
d) B if the current is small and A if the current is large
Answer: a

A ssertion-Reason Type Questions
For question numbers 1 and 2, two statements are given-one labeled as Assertion (A) and the other labeled Reason (R). Select the correct Answer: to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both ‘A’ and ‘R’ are true and ‘R’ is correct explanation of the Assertion.
(b) Both ‘A’ and ‘R’ are true but ‘R’ is not correct explanation of the Assertion.
(c) ‘A’ is true but ‘R’ is false.
(d) ‘A’ is false but ‘R’ is true.

Question:
Assertion: Magnetic field lines do not intersect.
Reason: Magnetic field lines are closed curves.
Answer: b

Question:
Assertion: A compass needle gets defected when electric current is passed through the nearly metallic wire.
Reason: The S.I unit of magnetic field strength is Oersted.
Answer: c

For question numbers 1 and 2 two statements are given-one labeled as Assertion (A) and the other labeled Reason (R). Select the correct Answer: to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both ‘A’ and ‘R’ are true and ‘R’ is correct explanation of the Assertion.
(b) Both ‘A’ and ‘R’ are true but ‘R’ is not correct explanation of the Assertion.
(c) ‘A’ is true but ‘R’ is false.
(d) ‘A’ is false but ‘R’ is true.

Question:
Assertion: Compass is a small magnet and gives direction of magnetic field lines.
Reason: It gets deflected when brought near a bar magnet.
Answer: b

Question:
Assertion: A current carrying solenoid behaves like a bar magnet.
Reason: When soft iron is placed inside the solenoid it can also be magnetised.
Answer: b

Question:
Assertion: Galvanometer is used to detect current.
Reason: Ammeter is used measure current generated in A.C. generator
Answer: b

Question:
Assertion: When the direction of movement of coil is reversed, the direction of induced current is also reversed.
Reason: Fleming’s right hand thumb rule detects the direction of induced current.
Answer: c

Fill in the Blanks :

Question: The unit of magnetic field is ………………….
Answer: tesla

Question: The field lines about the wire consist of a series of concentric circles whose direction is given by the ………… rule.
Answer: right-hand

Question: In our houses we receive AC electric power of ……… with a frequency of …………..
Answer: 220 V, 50 Hz.

Question: Magnetic field lines emerge from the …………. pole of a solenoid or a permanent magnet.
Answer: North

Question: The frequency for A.C. (alternating current) in USA is …………….
Answer: 60 Hz

Question: Field lines are used to represent a ……………. .
Answer: magnetic field

Question: You are looking down the axis of a solenoid, and the current from your position is clockwise. The end of the solenoid facing you is a ………….. pole.
Answer: south

Question: A compass needle is a ……………….. magnet.
Answer: small

Question: Crowding the wires of a solenoid more closely together will ………….. the strength of the field inside it.
Answer: increase

Question: You are looking into a solenoid, at its S-pole, along its axis. From your view point, the direction of the current in the solenoid is …………….
Answer: clockwise

True / False :

Question: A current-carrying conductor when placed in a magnetic field always experiences a force.
Answer: False

Question: A magnetic field exists in the region surrounding a magnet, in which the force of the magnet can be detected.
Answer: True

Question: The direction of force on a current carrying conductor placed in a magnetic field cannot be reversed by reversing the direction of magnetic field.
Answer: False

Question: The field lines inside the infinite solenoid are in the form of parallel straight lines.
Answer: True

Question: An electric generator works on the principle of electromagnetic induction.
Answer: True