18 Alternating Currents Tutorial

4 ¼ö ß¾ effect (J 8 3 /1/1 0 ) steady culT ent, w hen passed through the sam e resistor, w o u ©¥d have an identical heating T he periodic current passes through a resistor, producing heat at a certain rate. S tate the (©¥©¥) the root - r n e a n - square current. (©¥» the average value of the current, T he figure above show s the variation w ith tim e t of a periodic current I . D eterm ine r r U 1 ï l A «ili) the m axim um power in the resistor. (ii) the m ean pow er in the resistor, (1) the peak value of the culT ent, resistor. ca©¥cu©¥ate A sinusoida©¥ aïtem ating culT ent of r. m . s . v a lue 5 . 0 A passes through a 4 . 0 Q «b» C a©¥culate the peak value of a 2 4 0 V m ains electń city supp©¥y . S P 1 . (a) W nat is m eant by the r. m . s . v a ©¥ue of an a©¥tem ating cu©¥T ent? S e©¥f - P ractice Q uestions 5 7 . E xplain how a diode is used for rectification af an alternating current. and output potential di¨¤erences, a n d the pń m ary and secondary currents? 5 6 . F or an idea©¥ transform er, w hat is the relationship betw een the turns ratio of w indings, the input 5 5 . E xp©¥ain the principle of operation of a sim ple iron - c o r e transform er. 5 4 . W nat is the relationship betw een r. m . s . a n d peak values for a sinusoidal current? a©¥tem ating current. 5 3 . D educe that the m ean pow er in a resistive ©¥oad is half the m axim um pow er for a sinusoidal frequency, peak value and root - m e a n s quare value? 5 2 _ A sinusoidal current is represented by the equation İ = I . s ln (a) t) . W hat is its period, an a©¥tem ating current? 5 1 . W nat is m eant by peń od, frequency, peak value and root - m e a n s quare current as applied to S elf - C heck Q uestions ¡¤

C a©¥cu©¥ate the Y q lat ¢æsensitivity of the c. r. o. 1 . 0 cm 团 团 1¡á国 üÞ国团 团üÞ国 ©¥国©¥国 ìé 为¡¢0 ©¥国ÞÌ国 国©¥©¥ ©¥团 团 1 .o cm îìÒì£üÞ国 1国©¥©¥©¥©¥ 团团¡á©¥üÞ国 国 团团©¥国 ©© ¡¢ ¡£ ß¾üÞ国 团 团©¥国国 is sw itched on . p -d. Is applied to the Y - input. T he r. m . s. v a lue of the applied p . d. Is 4 . 24 V . T he tim e - base T he diagram show s the display on a cathode - ray oscilloscope (c. r . o. ) w hen a sinusoidalS P 6 . (M odified from J 9 3 /0 2 0 ) A ssum ing the transform er is 1 0 0 % efficient, w hat are the m issing entries? 222222222222 .o 11llllllllll团 团 国ÍÝ团 团 国ÍÝ团 团 国 国团 团 国 国团 团 国ÍÝ团 团 国ÍÝ llllllllllll团 团 国ÍÝ团 团 国ÍÝ团 团 国ÍÝ团 团 国 旧团 团 国ÍÝ团 团 国ÍÝ llllllllllll团团团Ï¡üÞ国团团Ï¡üÞ国团团Ï¡üÞ国团团ìíÞÌ国 ÏÐ国 ÏÐ 5o24 0 Vp / v I lp / m A I©¥W t u ÞÌ国 ©¥ K / v /©¥ / m A N ©¥ tu rn s In a ©¥aboratory experim ent to test a transform er, a s tudent obtained the fo©¥©¥ow ing results.S P 5 . across the secondary coil. coil is connected across a variable resistor. S uggest ways in w hich you can decrease the p . d. T he prim ary coil of a transform er is connected to an alternating voltage supply . T he secondaryS P 4 . heater now dissipate energy? (N 2 0 0 0 /1/2 1 ) connected to a 3 4 0 V d. c.