Download CH13 - Magnetic Effects of Electric Current

CH13 - Magnetic Effects of Electric Current
Earth's Magnetic Field
(computer simulation)
MCQs
Q1: The two poles in a magnet have
(a) equal pole strength.
(b) unequal pole strength.
(c) can be same or different
(d) None of these
Answer: a
Q2:A magnet AB is broken into two pieces. What is the polarity of A, B, C and D?
(a) A, D: North & B,C: South
(b) A, B: North & C,D: South
(c) A,C: North & B,D: South
(d) A,D: South & B,C: North
Answer: c
Q3: Magnetic field lines:
(a) form closed curves
(b) cannot intersect
(c) are crowded near poles
(d) All of these
Answer: d
Q4: The correct field lines are:
Answer: a
Q5:Who had first observed the magnetic effect of an electric current first ?
(a) Faraday
(b) Oersted
(c) Volta
(d) Ampere
Answer: b
Q6: 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
Q7: With the help of which law the direction of a magnetic field can be decided ?
(a) Faraday's law
(b) Fleming's right hand rule.
(c) Right hand thumb rule
(d) Fleming's left hand rule.
Answer: b
Q8: Which of the following property of a proton can change while it moves freely in a magnetic
field? (There may be more than one correct answer.)
(a) mass
(b) speed
(c) velocity
(d) momentum
Answer: c
Q9: Which of the following correctly describes the magnetic field near a long straight wire?(a)
The field consists of straight lines perpendicular to the wire.
(b) The field consists of straight lines parallel to the wire.
(c) The field consists of radial lines originating from the wire.
(d) The field consists of concentric circles centred on the wire.
Answer: d
Q10: What is the field line of a magnetic field passing through the centre of current carrying
circular ring ?
(a) Circular
(b) Straight line
(c) Ellipse
(d) Magnetic field is zero at center.
Answer: b
Q11: Frequency of AC in India is
(a) 50 Hz
(b) 60 Hz
(c) 110 Hz
(d) 220 Hz
Answer: a
Q12: As we move away from a current carrying conductor, the spacing between the magnetic
lines of force
(a) decreases
(b) increases
(c) remains at equal distances
(d) none of these
Answer: b
Q13: A positively-charged particle (alpha-particle) projected towards west is deflected towards
north by a magnetic field. The direction of magnetic field is
(a) towards south
(b) towards east
(c) downward
(d) upward
Answer: d
Q14: Whose magnetic field is like a magnetic field of a bar magnet?
(a) Current carrying wire
(b) Current carrying ring.
(c) Current carrying solenoid
(d) Current carrying rectangular loop
Answer: c
Q15: A rectangular coil of copper wires is rotated in a magnetic field. The direction of the
induced current changes once in each
(a) two revolutions
(b) one revolution
(c) half revolution
(d) one-fourth revolution
Answer: c
Q16: From which of the following case, the current in the loop will not be induced ?
(a) The loop is moved in the direction of the magnet.
(b) The magnet is moved in the direction of the loop.
(c) The loop and magnet are moved in the opposite direction with the same speed.
(d) The loop and magnet are moved in one direction with the same speed.
Answer: d
Q17: The phenomenon of electromagnetic induction is
(a) the process of charging a body.
(b) the process of generating magnetic field due to a current passing through a coil.
(c) producing induced current in a coil due to relative motion between a magnet and the coil.
(d) the process of rotating a coil of an electric motor.
Answer: c
Q18: The device used for producing electric current is called a
(a) generator.
(b) galvanometer.
(c) ammeter.
(d) motor.
Answer: a
Q19: The essential difference between an AC generator and a DC generator is that
(a) AC generator has an electromagnet while a DC generator has permanent magnet.
(b) DC generator will generate a higher voltage.
(c) AC generator will generate a higher voltage.
(d) AC generator has slip rings while the DC generator has a commutator.
Answer: d
Q20: At the time of short circuit, the current in the circuit
(a) reduces substantially.
(b) does not change.
(c) increases heavily.
(d) vary continuously.
Answer: c