Advertisements
Advertisements
Question
How does a magnetic field set up by a solenoid change when cross-sectional area of solenoid is increased?
Advertisements
Solution
By having a solenoid of large diameter or more cross-sectional area, the intensity of magnetic field increases.
RELATED QUESTIONS
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?
State two ways of magnetising an iron piece?
Name the material used for making the armature of an electric bell. Give a reason for your answer.
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.
Electric bell ______.
The magnetic flux through a coil having 100 turns decreases from 5 milli weber to zero in 5 second. Calculate the e.m.f. induced in the coil.
How does a magnetic field set up by a solenoid change when strength of current in the solenoid is decreased?
State two advantages of an electromagnet over a bar magnet.
State the factors that can increase the speed of rotation of the coil in a D.C. motor.
State the position of armature coil relative to the direction of magnetic field, in a D. C. motor when the deflecting couple acting an the coil is maximum.
(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.
