All of the following statements about transformers are true, except:Group of answer choicesTransformers have two coil windings.Transformers can convert low voltage to high voltage.Transformers can convert high amperage to low amperage.Transformers only operate if the input current stays the same.

In a step-down transformer:(a) number of turns in primary coil are less than the secondary coil.(b) the primary and secondary coils are wound on separate steel cores(c) number of turns in primary coil are more than the secondary coil.(d) number of turns in primary coil are equal to the secondary coil

Transformers are an essential part of the National Grid.  What are they used for?To convert electricity from from a.c. to d.c. and vice versaTo adjust the supply of electricity according to how much energy is needed at a given timeTo improve the efficiency with which electrical energy can be transmitted around the countryTo allow energy to be transferred from one energy store to another2What name is given to the type of transformer which allows for the potential difference (‘voltage’) at which electricity is delivered to be increased?A high voltage transformerA boost transformerA step-up transformerA jump-up transformer3A current of 0.5 kA is flowing through a cable of resistance 20 Ω.  Calculate the power dissipated in the cable.5 × 106 W10 W10 kW5 W4There is a potential difference of 250 V across an electrical cable.  Calculate the amount of energy dissipated in the cable when a current of 100 A flows through it for 10 seconds.25 J2.5 J25,000 J250,000 J5A high voltage power cable transmits electrical energy with an efficiency of 0.8.  If 2 × 107 W of electrical power is supplied to one end of the cable, how much is transmitted to the opposite end?1.6 × 109 W4 × 106 W2.5 × 107 W1.6 × 107 W

1. If the secondary of a transformer has twice as many turns as the primary, is the secondary voltage lower than the primary voltage? 2. What are the essential parts of a transformer? Give the role that each of them plays? 3. What are the essential parts of an alternator? Give the role that each of them plays? 4. Name the sources of losses in a transformer? 5. Name the sources of losses in an alternator? 6. While repairing a transformer, a few turns were removed from the secondary winding. What's going to happen ? 7. An ideal transformer is a transformer with no primary or secondary windings. True or false ? Justify your answer ? 8. We consider an ideal transformer fed at the primary by a sinusoidal alternating voltage. • Its yield is equal to 1? True or false ? Justify your answer • Its transformation ratio is equal to 1? True or false ? Justify your answer • Show, by means of a diagram, how to connect three single-phase transformers in star-delta and star-zigzag? 9. Name one processes from which an electromotive force can arise in a conductor?

uring the open circuit test of a transformer*The secondary is supplied rated KVAPrimary is supplied with no-load currentPrimary is supplied current at high voltage.Primary is supplied rated voltage

Why a transformer cannot be used to step up D.C. voltage?