Alternating Current AC Direct Current DC 1 A

Alternating Current (AC) Direct Current (DC) 1. A current changing in magnitude and direction A non oscillatory current flowing in one direction, in after equal intervals of time is called alternating a circuit is called a direct current (DC). current (AC). 2. The oscillation of the alternating current occurs in Direct current flows in one direction and indicated a sinusoidal manner with time and hence is shown by by the symbol ~. 3. It is used in household electrical appliances. This type of current cannot be used on large scale of current for household purposes. 4. The frequency of alternating current is about 50 Hz The frequency of direct current is 0. in India.

Electric Motor Electric Generator 1. Electrical energy is converted to mechanical energy Mechanical energy is converted to electrical energy in an electric motor. electric generator. 2. It is based on the principle – If a current carrying It is based on the principle of electromagnetic induction. conductor is placed in a magnetic field it experiences force. 3. It is based on Flemings left hand rule. It is based on Flemings right hand rule. 4. It is used in mixers, blenders, refrigerators. It is used in power stations or small dynamos used to light bulbs in a bicycle. 5. To rotate the armature electric current is supplied. To rotate the armature mechanical energy like flowing water, steam etc. is used.

Answer 5 (c) – Electric Generator (DC) Strong magnets Carbon brushes

CHAPTER 4 - EFFECTS OF ELECTRIC CURRENT

Answer 7 (d) 1. While joule is the SI unit for energy, we often use the kilowatt-hour (k. Wh) instead. 2. This is due to the fact that a joule is an extremely small amount of energy. 3. If 1 k. W power is used for 1 hour, it will mean 1 k. W x 1 hr of electrical energy is used. 1 k. Wh =1 kilowatt hour = 1000 W × 3600 s = 3. 6 × 106 W - s = 3. 6 x 106 J