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प्रश्न
Given the input current 15 A and the input voltage of 100 V for a step-up transformer having 90% efficiency, find the output power and the voltage in the secondary if the output current is 3 A.
उत्तर
\[\text { Input current } = 15 A\]
\[\text { Input voltage } = 100 V\]
\[efficiency = 90 % = 90/100\]
\[\frac{\text { Output power }}{\text { Input power}} = 0 . 9\]
\[\frac{\text { Output power }}{\text { Input voltage} \text { times Input current }} = \frac{\text { Output power}}{15 \times 100} = 0 . 9\]
\[\text { Output power} = 15 \times 100 \times 0 . 9 = 1350 W\]
\[\text { Outpur current} = 3 A\]
\[\text { Output voltage } = \frac{\text { Output power}}{\text { Output current}} = \frac{1350}{3} = 450 V\]
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संबंधित प्रश्न
A group of students while coming from the school noticed a box marked "Danger H.T. 2200 V" at a substation in the main street. They did not understand the utility of a such a high voltage, while they argued, the supply was only 220 V. They asked their teacher this question the next day. The teacher thought it to be an important question and therefore explained to the whole class.
Answer the following questions:
(i) What device is used to bring the high voltage down to low voltage of a.c. current and what is the principle of its working ?
(ii) Is it possible to use this device for bringing down the high dc voltage to the low voltage? Explain
(iii) Write the values displayed by the students and the teacher.
Name the phenomenon ?
Describe briefly, with the help of labelled diagram, working of a step-up transformer.
A step-up transformer converts a low voltage into high voltage. Does it not violate the principle of conservation of energy? Explain.
A transformer lowers e.m.f. from 220 V to 15 V. If 400 W power is given in primary, calculate (i) the current in primary coil and (ii) the current in secondary coil.
The primary of a transformer has 40 turns and works on 100 V and 100 W. Find a number of turns in the secondary to step up the voltage to 400 V. Also calculate the current in the secondary and primary.
Mention the various energy losses in a transformer.
A power transmission line feeds input power at 2300 V to a stepdown transformer with its primary windings having 4000 turns. What should be the number of turns in the secondary in order to get output power at 230 V?
Draw the effective equivalent circuit of the circuit shown in figure, at very high frequencies and find the effective impedance.
What is a transformer?
For what purpose are the transformers used?
