Advertisements
Advertisements
प्रश्न
How does a magnetic field set up by a solenoid change when strength of current in the solenoid is decreased?
Advertisements
उत्तर
By decreasing the current flowing in the solenoid, the intensity of magnetic field decreases.
संबंधित प्रश्न
The diagram shows a coil wound around a U-shaped soft iron bar AB.
- What is the polarity induced at the ends A and B when the switch is pressed?
- Suggest one way to strengthen the magnetic field in the electromagnet.
- What will be the polarities at A and B if the direction of current is reversed in the circuit?
You are given an iron nail, a torch cell, and a long piece of insulated copper wire. With the help of a labelled neat diagram, describe in steps how you will make the nail, an electromagnet.
Name and state the rule by which polarity at the ends of a current carrying solenoid is determined.
Name the type of transformer shown in Fig. What changes will you observe regarding the brightness of the lamp, if
- the number of turns in the secondary is doubled? Explain.
- the part X of the transformer is removed?
- the core of the transformer is made out of copper?
- the A.C. supply is replaced by D.C.?
Answer the following in short.
Name a few common appliances that use electromagnets.
State the condition when an electric charge can give rise to a magnetic field.
State the position of armature coil relative to the direction of magnetic field, in a D. C. motor when the deflecting couple acting and the coil is minimum.
What is dynomo (a.c. generator)? State the principle on which it works.
A current-carrying solenoid is suspended so as to freely rotate in a horizontal plane. State in what direction will it rest. Give a reason for your answer.
or
When a solenoid that is carrying current is freely suspended, it comes to rest in a particular direction. Why does this happen?
(i) A straight wire conductor passes vertically through a piece of cardboard sprinkled with iron filings. Copy the diagram and show the setting of iron filings when a current is passed through the wire in the upward direction and the cardboard is tapped gently. Draw arrows to represent the direction of the magnetic field lines.
(ii) Name the law which helped you to find the direction of the magnetic field lines.
