- 1(current)
Q. No.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 |
 73%
From NCERT
AIPMT - 2007
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The primary has \(100\) turns with \(100\) V rms applied to it while the secondary has a total number of \(20\) turns, with the connection \(C\) made at the centre. The current \(i\) flowing towards \(C\) has the (rms) value:
1. \(2\) A
2. \(2\sqrt2\) A
3. \(\sqrt2\) A
4. zero
1. \(2\) A
2. \(2\sqrt2\) A
3. \(\sqrt2\) A
4. zero
Subtopic: Â Transformer |
From NCERT
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The primary of a transformer when connected to the DC battery of \(10\) Volt draws a current of \(1~\mathrm{mA}\). The number of turns of the primary and secondary windings are \(50\) and \(100\) respectively. The voltage in the secondary and the current drawn by the circuit in the secondary are respectively:
| 1. | \(20~\mathrm{V}\) and \(2.0~\mathrm{mA}\) |
| 2. | \(10~\mathrm{V}\) and \(0.5~\mathrm{mA}\) |
| 3. | zero and therefore no current |
| 4. | \(20~\mathrm{V}\) and \(0.5~\mathrm{mA}\) |
Subtopic: Â Transformer |
From NCERT
NEET - 2013
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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. \(0.37 ~\mathrm{A}\)
2. \(0.27 ~\mathrm{A}\)
3. \(2.7 ~\mathrm{A}\)
4. \(3.7 ~\mathrm{A}\)
1. \(0.37 ~\mathrm{A}\)
2. \(0.27 ~\mathrm{A}\)
3. \(2.7 ~\mathrm{A}\)
4. \(3.7 ~\mathrm{A}\)
Subtopic: Â Transformer |
 68%
From NCERT
NEET - 2023
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- 1(current)
Q. No.
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