Tag: transformers

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Questions Related to transformers

Multiple choice physics electro-magnetism applications of electromagnets transformer transformers

Transformers are used

  1. in DC circuit only

  2. in AC circuits only

  3. in both DC and AC circuits

  4. neither in DC nor in AC circuits
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Transformers work on the principle of voltage induction by the linkage of changing magnetic flux between between the two cores. Changing magnetic flux requires changing/alternating current. 
Transformers are used only in AC circuits. In DC circuits, no alternating/changing magnetic flux is produced to induce voltage in secondary from the primary terminals of the transformers.

Multiple choice physics electro-magnetism applications of electromagnets transformer transformers

How will you  relate the number of turns in the primary coil of a step-down transformer  to that in secondary coil ?

  1. has large number of turns

  2. is very heavily insulated

  3. is very thin

  4. all the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A step down transformer has more turns of wire on the primary coil and less turns of wire on the secondary coil. This makes a smaller induced voltage in the secondary coil. 

Multiple choice physics electro-magnetism applications of electromagnets transformer transformers

In a step down transformer, the number of turns in the primary is always :

  1. greater than the number of turns in the secondary

  2. less than the number of turns in the secondary

  3. equal to the number of turns in the secondary

  4. either greater than or less than the number of turns in the secondary
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In step down transformers, voltage in secondary coil decreases. and we know that 


$\dfrac { { E } _{ s } }{ { E } _{ p } } =\dfrac { { n } _{ s } }{ { n } _{ p } } $

So, number of turns decreases in secondary coil with respect to primary coil.

Multiple choice physics electro-magnetism applications of electromagnets transformer transformers

A transformer changes the voltage

  1. without changing the current and frequency

  2. without changing the current but changes the

    frequency

  3. without changing the frequency but changes the

    current

  4. without changing the frequency as well as the

    current
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A transformers changes an alternating potential difference from one value to another of greater or smaller value using the principle of mutual induction. so, in transformer current and voltage changes but frequency remains same.

Multiple choice physics electro-magnetism applications of electromagnets transformer transformers

Statement A: In a transformer, a large alternating current at low voltage can be transformed into a small alternating current at high voltage
Statement B: Energy in current carrying coil is stored in the form of magnetic field.

  1. A is true but B is false

  2. Both A and B are true

  3. A is false but B is true

  4. Both A and B are false
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Transformer is used to increase voltage and decrease current in the secondary coil with respect to primary coil or vice versa.
Energy in the coil is always stored in the form of magnetic field.

Multiple choice physics electro-magnetism applications of electromagnets transformer transformers

Transformers are used in

  1. d.c circuits only

  2. a.c. circuits only

  3. Both a.c and d.c circuits

  4. Integrated circuits
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Transformers are used only in A.C. Circuits because D.C. current could not produce changing flux which in turn not able to produce induced emf in the secondary coil of the transformer but A.C. Current produces changing flux.

Multiple choice physics electro-magnetism applications of electromagnets transformer transformers

A transformer works on the principle of :

  1. Self induction

  2. Mutual induction

  3. Coulomb law

  4. Ampere law
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The Voltage Transformer can be thought of as an electrical component rather than an electronic component. A transformer basically is very simple static (or stationary) electro-magnetic passive electrical device that works on the principle of Faraday’s law of induction by converting electrical energy from one value to another.

The transformer does this by linking together two or more electrical circuits using a common oscillating magnetic circuit which is produced by the transformer itself. A transformer operates on the principals of “electromagnetic induction”, in the form of  $Mutual$ $ Induction$.

Mutual induction is the process by which a coil of wire magnetically induces a voltage into another coil located in close proximity to it. Then we can say that transformers work in the “magnetic domain”, and transformers get their name from the fact that they “transform” one voltage or current level into another.