Advertisements
Advertisements
Question
Explain the magnetic field created by a current around a conductor from the figure.
Advertisements
Solution
- Consider a circuit connected as shown in the figure.
- A cardboard is placed around a thick copper wire. A magnetic needle is used to check the magnetic field around the wire.
- When a large current flows through the thick wire, the magnetic needle shows deflection. At different points on the cardboard, the needle points in different directions.
- When joined the directions shown by the needle, the lines formed indicate that the magnetic field produced around a current-carrying conductor is in the form of concentric circles.
- The deflection in the needle changes according to the current in the conductor. For a given current, if we move the compass needle away from the wire, its deflection decreases.
- The direction of the magnetic field formed around the conductor depends on the direction of the current and is given by the right-hand thumb rule.
- If the thumb of the right hand indicates the direction of the current then, the curled fingers indicate the direction of the magnetic field formed.
APPEARS IN
RELATED QUESTIONS
Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain.
Which effect of current can be utilised in detecting a current carrying wire concealed in a wall?
Fill in the following blank with suitable words:
If a coil is viewed from one end and the current flows in an anticlockwise direction, then this end is a ........... pole.
If the direction of electric current in a solenoid when viewed from a particular end is anticlockwise, then this end of solenoid will be:
(a) west pole
(b) south pole
(c) north pole
(d) east pole
For the coil in the diagram below, when the switch is pressed:
(a) what is the polarity of end A?
(b) which way will the compass point then?
What device reverses the current?
The north pole of a long bar magnet was pushed slowly into a short solenoid connected to a galvanometer. The magnet was held stationary for a few seconds with the north pole in the middle of the solenoid and then withdrawn rapidly. The maximum deflection of the galvanometer was observed when the magnet was ______.
If fuse of 250 mA, 500 mA, 1 A, 5 A and 10 A were available, which one would be the most suitable for protecting an amplifier rated at 240 V, 180 W?
In the Activity shown below, how do we think the displacement of rod AB will be affected if
- current in rod AB is increased
- a stronger horse-shoe magnet is used
- length of the rod AB is increased?
|
(b) State whether the following statements are true or false:
(i) Magnetic poles exist in pairs.
(ii) Global warming is a desirable aspect of the intensified greenhouse effect.
Name any two appliances which works on the phenomenon of magnetic effect of electric current.
Identify the given figure, write the labels of it.
A soft iron bar is introduced inside the current-carrying solenoid. The magnetic field inside the solenoid ____________.
Boojho made an electromagnet by winding 50 turns of wire over an iron screw. Paheli also made an electromagnet by winding 100 turns over a similar iron screw. Which electromagnet will attract more pins? Give reason.
Edison used a ______ wire coil is a vacuum glass and discovered the first electric bulb in 1879.
______ cells cannot be recharged after use.
An electric bell contains an ______, consisting of coils of insulated wire wound around
iron rods.
A student was asked to perform an experiment to study the force on a current carrying conductor in a magnetic field. He took a small aluminium rod AB, a strong horse shoe magnet, some connecting wires, a battery and a switch and connected them as shown. He observed that on passing current, the rod gets displaced. On reversing the direction of current, the direction of displacement also gets reversed. On the basis of your understanding of this phenomenon, answer the following questions:
- Why does the rod get displaced on passing current through it?
- State the rule that determines the direction of the force on the conductor AB.
-
- If the U-shaped magnet is held vertically and the aluminium rod is suspended horizontally with its end B towards due north, then on passing current through the rod from B to A as shown, in which direction will the rod be displaced?
- Name any two devices that use current carrying conductors and magnetic fields.
OR
Draw the pattern of magnetic field lines produced around a current carrying straight conductor held vertically on a horizontal cardboard. Indicate the direction of the field lines as well as the direction of current flowing through the conductor.
A rectangular loop ABCD carrying a current I is situated near a straight conductor XY, such that the conductor is parallel to the side AB of the loop and is in the plane of the loop. If a steady current I is established in the conductor as shown, the conductor XY will ______.
