Q. No.Electrical energy is transmitted over large distances at high alternating voltages. Which of the following statements is (are) correct?
Choose the correct options:
| (a) | For a given power level, there is a lower current. |
| (b) | Lower current implies less power loss. |
| (c) | Transmission lines can be made thinner. |
| (d) | It is easy to reduce the voltage at the receiving end using step-down transformers. |
| 1. | (a), (b), (c) | 2. | (a), (b), (d) |
| 3. | (b), (c), (d) | 4. | (c), (d) |
Subtopic: Â Transformer |
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Level 2: 60%+
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A transformer is used to light a \(100~\text{W}\) and \(110~\text{V}\) lamp from a \(220~\text{V}\) main. If the main current is \(0.5~\text{A},\) the efficiency of the transformer is approximately:
1. \(30\%\)
2. \(50\%\)
3. \(90\%\)
4. \(10\%\)
Subtopic: Â Transformer |
 74%
Level 2: 60%+
AIPMT - 2007
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A transformer operating at a primary voltage of \(8\) kV and secondary voltage of \(160\) V serves a load of \(80\) kW. Assuming the transformer to be ideal with purely resistive load and working on unity power factor, the loads in the primary and secondary circuit would be:
| 1. | \(800~\Omega\) and \(1.06~\Omega\) | 2. | \(10~\Omega\) and \(500~\Omega\) |
| 3. | \(800~\Omega\) and \(0.32~\Omega\) | 4. | \(1.06~\Omega\) and \(500~\Omega\) |
Subtopic: Â Transformer |
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Level 1: 80%+
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A transformer has an efficiency of \(80\text{%}.\) It works at \(40\) kW and \(100\) V. If the secondary voltage is \(240\) V, the current in the secondary coil is nearly:
1. \(40\) A
2. \(133.3\) A
3. \(86.7\) A
4. \(112\) A
1. \(40\) A
2. \(133.3\) A
3. \(86.7\) A
4. \(112\) A
Subtopic: Â Transformer |
 88%
Level 1: 80%+
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A transformer with \(8:1\) turns ratio has \(50~\text{Hz},\) \(100~\text V\) input. The frequency of the output is:
1. \(40~\text{Hz}\)
2. \(50~\text{Hz}\)
3. \(400~\text{Hz}\)
4. \(500~\text{Hz}\)
1. \(40~\text{Hz}\)
2. \(50~\text{Hz}\)
3. \(400~\text{Hz}\)
4. \(500~\text{Hz}\)
Subtopic: Â Transformer |
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Level 2: 60%+
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In an ideal transformer, the number of turns in primary and secondary coils are \(500\) and \(2000\) respectively. If the current in the primary coil is \(48~\text{A},\) then the current in the secondary coil will be:
1. \(12~\text{A}\)
2. \(24~\text{A}\)
3. \(48~\text{A}\)
4. \(144~\text{A}\)
1. \(12~\text{A}\)
2. \(24~\text{A}\)
3. \(48~\text{A}\)
4. \(144~\text{A}\)
Subtopic: Â Transformer |
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Level 1: 80%+
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A step-down transformer connected to an AC mains supply of \(220~\text{V}\) is made to operate at \(11~\text{V},\) \(44~\text{W}\) lamp. Ignoring power losses in the transformer, what is the current in the primary circuit?
1. \(2~\text{A}\)
2. \(4~\text{A}\)
3. \(0.2~\text{A}\)
4. \(0.4~\text{A}\)
1. \(2~\text{A}\)
2. \(4~\text{A}\)
3. \(0.2~\text{A}\)
4. \(0.4~\text{A}\)
Subtopic: Â Transformer |
 70%
Level 2: 60%+
NEET - 2021
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An ideal transformer has \(100\) turns in the primary coil and carries a \(5\) A current. To achieve a \(1600\) V output with a \(2\) kW power output, the number of turns in the secondary coil must be:
1. \(100\)
2. \(200\)
3. \(300\)
4. \(400\)
1. \(100\)
2. \(200\)
3. \(300\)
4. \(400\)
Subtopic: Â Transformer |
 84%
Level 1: 80%+
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A \(12~\text{V},60~\text{W}\) lamp is connected to the secondary of a step-down transformer, whose primary is connected to AC mains of \(220~\text{V}\). Assuming the transformer to be ideal, what is the current in the primary winding?
1. \(0.37~\text{A}\)
2. \(0.27~\text{A}\)
3. \(2.7~\text{A}\)
4. \(3.7~\text{A}\)
1. \(0.37~\text{A}\)
2. \(0.27~\text{A}\)
3. \(2.7~\text{A}\)
4. \(3.7~\text{A}\)
Subtopic: Â Transformer |
 74%
Level 2: 60%+
NEET - 2023
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A power transmission line feeds input power at \(2300~\text V\) to a step-down 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 \(230~\text V?\)
1. \(200\)
2. \(250\)
3. \(350\)
4. \(400\)
Subtopic: Â Transformer |
 80%
Level 1: 80%+
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