Advertisements
Advertisements
प्रश्न
State the principle of a D. C. motor.
Advertisements
उत्तर
It is based on the principle that when an electric current is passed through a conductor placed normally in a magnetic field, a force acts on the conductor as a result of which the conductor begins to move. The direction of the force is obtained with the help of Fleming’s left hand rule.
संबंधित प्रश्न
The diagram shows a coil wound around a U shape soft iron bar AB.
1) What is the polarity induced at the ends A and B when the switch is pressed?
2) Suggest one way to strengthen the magnetic field in the electromagnet
3) What will be the polarities at A & B if the direction of current is reversed in the circuit?
How will you make an iron bar electromagnet? Draw a diagram showing the polarities of the electromagnet?
Suppose you are given a long bar magnet and you are asked to break it into four small magnets. Draw diagrams showing the polarities of each broken part.
Name and state the rule by which polarity at the ends of a current carrying solenoid is determined.
State three uses of an electromagnet?
Name the material of core in (a) an electric bell, (b) electromagnet, (c) a d.c. motor, (d) an a.c. generator and (e) a transformer.
Fill in the blanks by writing (i) Only soft iron, (ii) Only steel, (iii) Both soft-iron and steel for the material of core and/or magnet.
Electromagnet ______.
What is a permanent magnet? Give one use of it.
State the factors that can increase the speed of rotation of the coil in a D.C. motor.
How does a magnetic field set up by a solenoid change when cross-sectional area of solenoid is increased?
