Saved Bookmarks
| 1. |
The teachers of Geeta's school took the students on a study tirp to a power generating station, loactad nearly 200km away form thecity.Theteacher explained that electrical energy is transmitted over sucha longdistance to their city, in the form of alternatingcurrent (ac) raised to a high voltage. At the receiving endis the city,the voltageis reduced to operate the devices. As a result, the powerloss is reduced. Geeta listened to theteacher and asked question abouthowthe ac isconverted to a higheror lower voltage. (a) Name th device used to change the alternatingtoa higheror lower value. State one cause for power dissipationin thisdevice. (b) Explainwith an example, howpower lossis reduced if theenergy is transmitted overlongdistance as an alternatingcurrentrather than a direct current, (c) Write two values each shown by theteachers and Geeta. |
|
Answer» Solution :(a) The device whichconverts high voltageto low or low voltageto high voltageis called tranformer. Power can LOSS byheat and FLUX leakage. (b) Electricpowerlis transmitted FORM powerstation to homes through cable. These cables haveresistance power P is deliverd to load R via cables resistance `R_(l)` if v isvolt across load R andI current. `P = V - I` Power wasted `P_(l) = I^(2)R_(t) = (P^(2)Rt)/(V^(2))` `P_(t) prop (I)/(V^(2))` highvolt WASTE loss power. (c) They shouldbe polite and thankful to each other. |
|