CBSE X Science Magnetic Effects of Current - EducareHut (Next Gen Knowledge Point)

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#1. Fleming’s left hand and Right hand rules are used in

Generator and electric motor

Electric motor and generator

any rule can be used for any device

both are not applied for generator and motor.

Explanation: Electric motor employs Fleming left hand rule while for generator, Fleming right-hand rule is used.

#2. The magnetic field lines always begin from

N-pole and end on S-pole.

S-pole and end on N-pole.

start from the middle and end at N-pole.

start from the middle and end at S-pole.

#3. Direction of rotation of a coil in electric motor is determined by

fleming’s right hand rule

fleming’s left hand rule

faraday law of electromagnetic inductors

None of answer

Explanation: (b) Fleming’s left hand rule.

#4. A magnet is moved towards a coil (i) quickly (ii) slowly. The induced potential difference

#5. The strength of magnetic field around a current carrying conductor is

inversely proportional to the current but directly proportional to the square of the distance from wire.

directly proportional to the current and inversely proportional to the distance from wire.

directly proportional to the distance and inversely proportional to the current

directly proportional to the current but inversely proportional the square of the distance from wire.

Explanation:
• Magnetic field strength increases on increasing the current through the wire.
• Magnetic field strength decreases as the distance from the wire increases.

#6. The condition for the phenomena of electromagnetic induction is that there must be a relative motion between

the galvanometer and magnet

the coil of wire and galvanometer

the coil of wire and magnet

the magnet and galvanometer

Explanation: (c) The relative motion between the magnet and coil of wire causes change in magnetic field lines linked with the coil to produces induced current if the circuit is closed.

#7. At the time of short circuit, the current in the circuit

Reduces substantially.

Does not change.

Increases heavily.

Vary continuously.

#8. The strength of each of magnet reduces to half when it cut along its length into the equal parts magnetic field strength of a solenoid. Polarity of solenoid can be determined by

use of compass needle

Right hand thumb rule

fleming left hand rule

either (a) or (b)

Explanation: (d) both (a) and (b) can be use to determine the polarity of solenoid.

#9. The essential difference between an AC generator and a DC generator is that

AC generator has an electromagnet while a DC generator has permanent magnet.

DC generator will generate a higher voltage.

AC generator will generate a higher voltage.

AC generator has slip rings while the DC generator has a commutator.

#10. The instrument that use to detect electric current in the circuit is known as

electric motor

A.C generator

galvanometer

none of the above

Explanation: A galvanometer is an instrument that can direct the presence of current in a circuit.

#11. The magnetic field lines outside a bar magnet:

Originate from the South pole and end at its North Pole

Originate from the North pole and end at its East Pole

Originate from the North Pole and end at its South Pole

Originate from the South pole and end at its West Pole

#12. The frequency of electricity produced by DC generator is equal to

0 Hz

50 Hz

100 Hz

200 Hz

#13. Which of the following diagrams correctly shows the magnetic field produced by a current- carrying wire?

#14. For a current in a long straight solenoid, N and S-poles are created at the two ends. Among the following statements, the incorrect statement is

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

The strong magnetic field produced inside the solenoid can be used to magnetise a piece of magnetic material like soft iron, when placed inside the coil

The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet

The N and S-poles exchange position when the direction of current through the solenoid is reversed

Explanation: Option (a), (b) and (d) are correct. Only option (c) is incorrect because the pattern of magnetic fields due to solenoid and bar magnet is almost same.

#15. The main advantage of A.C power transmission over D.C power transmission over’ long distance is

AC transmit without much loss of energy

less insulation problem

less problem of instability

easy transformation.

Explanation: AC transmit over a long distance without much loss of energy as compare to DC.

#16. The best material to make permanent magnets is

aluminium

soft iron

copper

alnico

#17. Magnetic lines of force inside current carrying solenoid are

perpendicular to axis.

along the axis and are parallel to each other.

parallel inside the solenoid and circular at the ends.

circular.

#18. Which of the following factors affect the strength of force experience by a current carrying conduct in a uniform magnetic field?

magnetic field strength

magnitude of current in a conductor

length of the conductor within magnetic field

All of the other 3 Answers.

Explanation: (d) All the factors affect the strength of magnetic force.

#19. What should be the core of an electromagnet?

soft iron

hard iron

rusted iron

none of answer

#20. A positive charge is moving towards a person. The direction of magnetic field lines will be in

Clockwise direction

Anticlockwise direction

Vertically upward direction

Vertically downward direction

#21. Switches are connected to

live wire

neutral wire

earth wire

any one

#22. A fuse should always be placed in the

Live wire of the main circuit

Neutral wire of the main circuit

Earth wire of the main circuit

Both live and neutral wire of the main circuit.

#23. A coil of insulated copper wire is connected to a galvanometer forming a loop and a magnet id. A: Held stationary B: Moved away along its axis C: Moved towards along its axis.There will be a induced current in:

A only

A and B only

B and C only

A, B and C

#24. When current is parallel to magnetic field, then force experience by the current carrying conductor placed in uniform magnetic field is

Twice to that when angle is 60°

Thrice to that when angle is 60°

zero

infinite

Explanation: (a) If the current direction is parallel to the magnetic field, then there will no force on the conductor exerted by the magnetic field.

#25. The magnetic field is the strongest at

middle of the magnet.

north pole.

south pole.

both poles.

Finish