Primary, Secondary Voltages in Transformer

Q.

What is the output of transformer AC or DC?

Q.

Alternating current can not be measured by dc ammeter because

[AIEEE 2004]

1. Average value of complete cycle is zero

2. ac is virtual

3. ac changes its direction

4. ac cannot pass through dc ammeter

Q. The primary coil of a transformer contains 100 turns; the secondary has 200 turns. The primary coil is connected to a size AA battery that supplies a constant voltage of 1.5 volts.The voltage in the secondary coil will be volts.

1. \N
2. 0.75
3. 3
4. 1.5

Q. A transformer working on a 240 V A.C. supplies a voltage of 8 V to an electric bell. The number of turns in primary coil is 4800. What is the number of turns in the secondary coil?

1. 2400
2. 800
3. 160
4. 600

Q.

Name the principle on which a transformer works. Can a transformer work when connected to a D.C. source?

1. Mutual Induction, Yes as transformer works on DC and AC

2. Mechanical effect of Electric current, No as transformer works only on AC

3. Mechanical effect of Electric current, Yes as transformer works on DC and AC

4. Mutual Induction, No as transformer works only on AC

Q.

A transformer has 1500 turns in the primary coil and 1125 turns in the secondary coil. If the voltage in the primary coil is 200 V, then the voltage in the secondary coil is

1. 100 V

2. 200 V

3. 250 V

4. 150 V

Q.

The number of turns in the primary coil of a transformer are $100$ and that in the secondary coil are $200$. What type of transformer is it? If the input voltage in the primary coil of the transformer is $200V$, find the output voltage in the secondary coil of the transformer.

Q. A step-down transformer is to be constructed to obtain an output voltage of 60 V by applying an input voltage of 110 V. If the primary coil has 6600 turns, then the number of turns of the secondary coil will be ___

Q. In a cyclotron, why we use a high frequency alternating voltage for the dees. What will happen in case of a DC connection or if the frequency is low?

Q.

The number of turns in primary and secondary windings of a transformer are 1000 and 100 respectively. If 200 V DC voltage is applied across the primary terminal, then the voltage across the secondary terminal is

1. 22 V

2. 2200 V

3. 220 V

4. 0 V

Q. Assertion :A $60W$ bulb is connected in parallel with a room heater and this combination is connected across the mains. If the $60W$ bulb is replaced by a $100W$ bulb, the heat produced by the heater will be more . BECAUSE Reason: When resistances are connected in parallel across the mains, the heat produced is inversely proportional to the resistance

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Q. If the switches $S_1,S_2$ and $S_3$ in the figure are arranged such that current through the battery is minimum, find the voltage across points $A$ and $B$.(rounded off to nearest integer)

Q. Electric voltage is converted to $220V$ before distribution by using

1. Step down transformer
2. Step up transformer
3. Both
4. None of these