Advertisements
Advertisements
प्रश्न
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.
Advertisements
उत्तर
The deflecting couple acting on the coil is minimum when the plane of the coil is normal to the direction of magnetic field.
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?
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.?

State two factors on which the magnitude of an induced e.m.f. in the secondary coils of a transformer depends.
Answer the following in short.
Name a few common appliances that use electromagnets.
How does a magnetic field set up by a solenoid change when a soft iron core is inserted inside solenoid?
State the condition when an electric charge can give rise to a magnetic field.
What energy conversion takes place during the working of a d c motor?
The primary windings of a step-up transformer are usually made of thicker wire than the secondary. Explain.
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?
