# NCERT Class X Science Class: Chapter –13. Magnetic Effects of Electric Current – Part-5

Question 20:

What does the divergence of magnetic field lines near the ends of a current carrying straight solenoid indicate?

The divergence (degree of closeness) of magnetic field lines near the ends of a current carrying straight solenoid indicates a decrease in the strength of the magnetic field near the ends of the solenoid.

Question 21:

Name four appliances wherein an electric motor, a rotating device that converts electrical energy to mechanical energy, is used as an important component. In what respect motors are different from generators?

The four appliances such as electric fans, washing machines, mixers grinders, electric drills, tape recorders, etc., use an electric motor as a rotating device that converts electrical energy to mechanical energy.The motor is a machine which converts the electric energy into mechanical energy.The generator is the device which converts mechanical energy into electrical energy. It is used to convert the mechanical power to electric power which varies in the magnitude with a specific frequency.

Question 22:

What is the role of the two conducting stationary brushes in a simple electric motor?

The brushes are connected to the battery and touch the outerside of two halves of the split ring whose inner sides are insulatedand attached to the axle.

Question 23:

What is the difference between a direct current and an alternating current? How many times does AC used in India change directionin one second?

Direct current always flows in one direction but the alternatingcurrent reverses its direction periodically. The frequency of AC inIndia is and in each cycle it alters direction twice. ThereforeAC changes times in one second

Question 24:

What is the role of fuse, used in series with any electrical appliance? Why should a fuse with defined rating not be replaced by one with a larger rating?

Fuse is used for protecting appliances due to short-circuiting oroverloading. The fuse is rated for a certain maximum current andblows off when a current more than the rated value flows throughit. If a fuse is replaced by one with larger ratings, the appliancesmay get damaged while the protecting fuse does not burn off. Thispractice of using fuse of improper rating should always be avoided.

Question 25:

Why does a magnetic compass needle pointing North and South in the absence of a nearby magnet get deflected when a bar magnet or a current carrying loop is brought near it. Describe some salient features of magnetic lines of field concept.