The O$.$C and S$.$C test data are given below for a single phase, $20$kVA,$2200\frac{V}{220}V,50Hz$ transformer.

O$.$C test from LV side: $220V,4\mathrm{.}2A,148W$

S$.$C test from HV side: $74\mathrm{.}5V,9\mathrm{.}1A,270\mathrm{.}4W$;

$20.$Equivalent resistance referred to primary is

$$:

$)3\mathrm{.}27$

B$)0\mathrm{.}0327$

C$)2\mathrm{.}48$

D$)0\mathrm{.}0248$

$21.$Equivalent resistance referred to secondary is $$:

A$)3\mathrm{.}27$

B$)0\mathrm{.}0327$

C$)2\mathrm{.}48$

D$)0\mathrm{.}0248$

$22.$ Equivalent reactance referred to primary is

$($k$)7\mathrm{.}51$

B$)0\mathrm{.}0751$

C$)9\mathrm{.}36$

$$:

$23.$Equivalent reactance referred to secondary is

D$)0\mathrm{.}0936$

A$)7\mathrm{.}51$

$)0\mathrm{.}0751$

C$)9\mathrm{.}36$

$$ :

$24.$ Regulation of transformer at $0\mathrm{.}8$ pf $.$ lagging current is

A$)3\mathrm{.}57$

B$)3\mathrm{.}93$

C$)2\mathrm{.}94$

$25.$Efficiency at full $-$ load at $0\mathrm{.}8$ pf $.$ lagging current is

A$)97\mathrm{.}71$

B$)97\mathrm{.}77$

$($C$)97\mathrm{.}45$

D$)0\mathrm{.}0936$

$26.$ Copper losses at half the full$-$load at $0\mathrm{.}8$ pf $.$ lagging current is

A$)320$

B$)80$

C$)270\mathrm{.}4$

W:

$27.$ Core losses at half the full$-$load at $0\mathrm{.}8$ pf $.$ lagging current is

A$)148$

B$)296$

C$)74$

w:

D$)37$

CS

For the network shown in the following figure, $V_1=15V$;$V_2=30V$

$28.$ The output voltage $V$ of the following circuit

A$)5$ V

B$)25$ V

C$)12$ V

$)15$ V

$29.$ The current flow in the $R_1$

A$)0\mathrm{.}05$ A

B$)0$ A

C$)0\mathrm{.}15$ A

D$)0\mathrm{.}2$ A

$30.$ The current flow in the $R_2$

A$)0\mathrm{.}05$ A

B$)0$ A

C$)-0\mathrm{.}15$ A

D$)-0\mathrm{.}2$ A