Alternating Current | Physics JEE Main questions with Solutions

0

072920 77839
info@smartachievers.in

Topic Question Set

Q 1 :
Primary side of a transformer is connected to 230 V, 50 Hz supply. Turns ratio of primary to secondary winding is 10 : 1. Load resistance connected to secondary side is 46 Ω. The power consumed in it is [2024]

12.5 W
10.0 W
11.5 W
12.0 W

1

2

3

4

(C) $\frac{V_{1}}{V_{2}} = \frac{N_{1}}{N_{2}}$

$\frac{230}{V_{2}} = \frac{10}{1}$

$V_{2} = 23 V$

$Power consumed = \frac{V_{2}^{2}}{R} = \frac{23 \times 23}{46} = 11.5 W$

Q 2 :
A transformer has an efficiency of 80% and works at 10 V and 4 kW. If the secondary voltage is 240 V, then the current in the secondary coil is [2024]

1.59A
13.33 A
1.33 A
15.1 A

1

2

3

4

(B) $Efficiency η = 80 %, P_{i} = 4 kW = 4000 W$

$V_{P} = 10 V,$ $V_{S} = 240 V$

$For primary coil : I_{P} = \frac{P_{i}}{V_{P}} = \frac{4000}{10} = 400 A$

$η = \frac{V_{S} I_{S}}{V_{P} I_{P}} \Rightarrow \frac{80}{100} = \frac{240 I_{S}}{10 \times 400}$

$\Rightarrow I_{S} = 13.33 A$

Q 3 :
A power transmission line feeds input power at 2.3 kV to a step down transformer with its primary winding having 3000 turns. The output power is delivered at 230 V by the transformer. The current in the primary of the transformer is 5 A and its efficiency is 90%. The winding of transformer is made of copper. The output current of transformer is _____A. [2024]

0%

(45) $0.9 P_{i} = P_{o u t}$

$P_{i} = V I$

$P_{i} = 2.3 \times 10^{3} (5) = 11.5 \times 10^{3} W$

$P_{o u t} = (230) i_{2}$

$(0.9) (11.5 \times 10^{3}) = 230 i_{2}$

$i_{2} = \frac{(0.9) (11.5 \times 10^{3})}{230} = 0.045 \times 10^{3}$

$i_{2} = 45 A$

Want Us to Email you About Special Offers & Updates?