The figure given below shows an electromagnet.
i) What will be the polarity at the end X?
ii) Suggest a way by which the strength of the electromagnet referred to in the question, may be increased.i) Polarity at the end X is North (I = anticlockwise)
ii) It can be increased by increasing the strength of the current or even by increasing the number of turns of the coil.
i) What is an a.c. generator or dynamo used for?
ii) Name the principle on which it works?The diagram below shows a current carrying loop or a circular coil passing through a sheet of cardboard at the points M and N. The sheet of cardboard is sprinkled uniformly with iron fillings. 
i) Copy the diagram and draw an arrow on the circular coil to show the direction of current flowing through it.
ii) Draw the pattern of arrangement of the iron fillings when current is passed through the loop.Give two differences between a d.c. motor and an a.c generator.
A device is used to transform 12 V a.c. to 200 V a.c.
i) What is the name of this device?
ii) Name the principle on which it works.
i) A straight wire conductor passes vertically through a piece of cardboard sprinkled with iron fillings. Copy the diagram and shows the setting of iron fillings when a current is passed through the wire in the upward direction and the cardboard is tapped gently. Draw an arrow 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.
i) State two ways by which the magnetic field of a solenoid can be made stronger.
ii) What material is used for making the armature of an electric bell? Give a reason for using this material.The figure given below shows an electromagnet.
i) What will be the polarity at the end X?
ii) Suggest a way by which the strength of the electromagnet referred to in the question, may be increased.i) Draw a neat and labelled diagram to show the structure of an a.c. generator.
ii) State the energy conversion taking place in the generator when it is working.State the energy change which takes place when a magnet is moved inside a coil having a galvanometer at its ends. Name this phenomenon.
Draw a labeled diagram of an A.C. generator.
Mock Test Series
