Electromagnetism and Electromagnet
Trending Questions
What is an electromagnet ? Name two factors on which the strength of magnetic field of an electro-magnet depends and state how does it depend on the factors stated by you.
(a) What is an electromagnet ? Describe the construction and working of a electromagnet with the help of a labelled diagram.
(b) Explain why an electromagnet is called a temporary magnet.
(c) Explain why the core of an electromagnet should be made of soft iron and not of steel.
(d) State the factors on which the strength of an electromagnet depends. How does it depend on these factors ?
(e) Write some of the important uses of electromagnets.
Name some electrical appliances in which electromagnets are used.
How can you increase the strength of the magnetic field produced by the solenoid?
A soft iron bar is inserted inside a current-carrying solenoid. The magnetic field inside the solenoid :
(a) will decrease (b) will increase
(c) will become zero (d) will remain the same
- Diamagnetic
- Paramagnetic
- Ferromagnetic
- Nonmagnetic
The north-south polarities of an electromagnet can be found easily by using :
(a) Fleming's right-hand rule (b) Fleming's left-hand rule
(c) Clock face rule (d) Left-hand thumb rule
What is an electromagnet? List any two uses.
Mark ‘T’ if the statement is true and ‘F’ if it is false: An electromagnet does not attract a piece of iron. (T/F)
- True
- False
The poles of an electromagnet can be reversed. Give the reason.
The strength of the magnetic field between the poles of an electromagnet would be unchanged if :
(a) current in the electromagnet winding were doubled
(b) direction of current in electromagnet winding were reversed
(c) distance between the poles of electromagnet were doubled
(d) material of the core of electromagnet were changed
An electromagnet loses its magnetism when the current is switched off.
- True
- False
Is titanium magnetic material?
The diagram in the figure shows a coil wound around a soft iron bar XY.
(a) State the polarity at the ends X and Y as the switch is pressed.
(b) Suggest one way of increasing the strength of electromagnet so formed.
- Increase the number of turns in the coil.
- Decrease the current flowing the coil.
- Increase the current flowing through the coil.
- Remove the soft iron core.
(a) Draw a circuit diagram to show how a soft iron piece can be transformed into an electromagnet.
(b) Describe how an electromagnet could be used to separate copper from iron in a scrap yard.
What happens when a soft iron bar is inserted in a current carrying solenoid
If a current carrying conductor is placed near a heap of iron filings, we can observe some disturbance in iron filings, because of
None of these
Electric field produced by current
Gravitational field
Magnetic field produced by current
An insulated copper wire is wound on a soft iron core. Current is passed through the coil such that at end ‘A’ the current flows anti- clockwise and a magnetic compass needle placed at other end ‘B’ of the coil.
i) If soft iron core is replaced by a cardboard tube, what will be the effect on the magnetic needle?
ii) What happens to the magnetic needle if the current is stopped?
i) The amount of deflection will increase ii) The needle will not be affected
i) The amount of deflection will increase ii) The needle will return to its original position
i) The amount of deflection will decrease ii) The needle will remain deflected
i) The amount of deflection will decrease ii) The needle will deflect in the opposite direction
i) The amount of deflection will decrease ii) The needle will return to its original position
- False
- True
Look at the figure given below and answer the question based on it.
Iron filings are sprinkled on a cardboard perpendicular to which a current carrying copper wire runs. The other components of the circuit have their usual meanings.
The deflection of the compass needle decreases as the compass is moved away from the copper wire. This tells us that?
The magnetic field strength increases as the distance from the wire increases
The magnetic field strength decreases as the distance from the wire increases
There is no change in the magnetic field strength
The magnetic field alters its direction as distance from the wire increases
Electricity and magnetism are said to be inter-related to each other. A current carrying conductor has a magnetic field around it. So, when a compass is brought near to it, we can observe a deflection in the compass. Similarly, a battery is the source of the electric current. What will be the deflection, when we bring a compass near a 3 V cell (battery)?
The needle will be deflected towards the cell.
The needle will be deflected away from the cell.
The needle will show no deflection and point towards geographical north.
None of these
Considering a long current carrying solenoid. 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 completely same as 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
Listed below is the use of magnets and electromagnets. Indicate whether a permanent magnet or an electromagnet is used with an explanation.
Television
Give one word for the following.
A temporary magnet depends on the magnetic effect of the current.
- Circular
- Straight line
- Ellipse
- Magnetic field is zero at the centre
