# The ratio of the primary to secondary voltage of a transformer is 2:1. The saving in the turns of weight of...

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The ratio of the primary to secondary voltage of a transformer is 2:1. The saving in the turns of weight of copper required if an autotransformer is used instead of two winding transformer is (1) 50% (2) 33.33% (3) 66.67% (4) 97%

## Related questions

The turns ratio of a transformer having 200 primary turns and 1,200 secondary turns is? A.6 B.24 C.1.66 D.66

When the turns ratio of a transformer is 20 and the primary ac voltage is 12 V, the secondary voltage is? A.12 V B.120 V C.240 V D.2,400 V

A single-phase transformer has a turns ratio of 1 :2 and is connected to a purely resistive load as shown in the figure. The magnetizing current drawn is 1A, and the secondary current is 1A. Ifcore losses and leakage reactances are neglected, the primary current is  A)1.41A B)2A C) 2.24A D)3A

A certain transformer has 400 turns in the primary winding and 2,000 turns in the secondary winding. The turns ratio is? A.0.2 B.0.4 C.5 D.25

If the secondary turns of a transformer are doubled and at the same time primary voltage is reduced to half then the secondary voltage will

An AC supply of 230 V is applied to half wave rectifier circuit. A transformer turns ratio is 20 : 1. Find i) Output DC voltage (ii) Peak Inverse Voltage (PIV)

A certain transformer has 200 turns in the primary winding, 50 turns in the secondary winding and 120 volts applied to the primary. What is the voltage across the secondary?  (A) 30 Volts (B) 480 Volts (C) 120 Volts (D) 60 Volts

If a transformer has 50 turns in the primary winding and 10 turns in the secondary winding, what is the reflective resistance if the secondary load resistance is 250 ohms? A.250 ohms B.25 ohms C.6,250 ohms D.62,500 ohms

What happens to the voltage in the secondary when the frequency of the supply in the primary is decreased? A) It increases B) It decreases C) It remains the same D) Cannot say unless the actual percentage increase in the frequency is known

In a certain loaded transformer, the secondary voltage is one-fourth the primary voltage. The secondary current is? A.one-fourth the primary current B.four times the primary current C.equal to the primary current D.one-fourth the primary current and equal to the primary current

A 1:5 step-up transformer has 120V across the primary and 600 ohms resistance across the secondary. Assuming 100% efficiency, the primary current will be:  (A) 0.2 Amp. (B) 5 Amps. (C)10 Amps. (D) 20 Amps

A single phase 230 V/ 150 V , 1 kVA, 50 Hz transformer is supplied by 230 V AC supply. Find the full load primary and secondary current.

In a transformer the energy is conveyed from primary to secondary?

In potential transformers, the secondary turns are increased slightly and the primary and secondary windings are wound as closely as possible to compensate for  (a) Phase angle and ratio error, respectively  (b) Ratio and phase angle error, respectively  (c) Any eddy current loss and hysteresis loss, respectively  (d) The hysteresis loss and eddy current loss, respectively

One 200 V, 100 W bulb is connected in series with primary of a 200 V, 10 kVA transformer. If its secondary is kept open circuited, then the bulb would have (1) Full brightness (2) Poor brightness (3) A little less than full brightness (4) More than full brightness

The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 ohms load. The turns ratio is 3:1. What is the secondary voltage? A.2 V B.20 V C.180 V D.18 V

Define: 1) voltage ratio, 2) current ratio, 3) transformation ratio of transformer.

The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be; (A) 3.6 (B) 2.5 V (C) 3.0 V (D) 6.0 V

if the rated voltage from the power lines is applied to the primary of a single-phase transformer which is operated on no-load, then

Increasing the number of turns of wire on the secondary of a transformer will  (A) Decrease the secondary current (B) Increase the primary current (C) Have no effect on the secondary current (D) Increase the secondary current

The primary turns of a 444 V/222 V, 50 Hz single-phase transformer with a core cross-sectional area of 100 cm2, and a maximum flux density of 1.0 T is (A) 100 (B) 200 (C) 222 (D) 400

In a three phase transformer, if the primary side is connected in star and secondary side is connected in delta, the angle difference between phase voltage in the two cases will be: (A) delta side will lag by -30° (B) star side will lag by -30° (C) delta side will lead by 30° (D) star side will lead by -30°

For a pulse transformer, the material used for its core and the possible turn ration from primary to secondary are respectively   (A) ferrite : 20 : 1 (B) laminated iron : 1 :1 (C) ferrite : 1 : 1 (D) powered iron : 1: 1

The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be (A) 3.6 V. (B) 2.5 V. (C) 3.0 V. (D) 6.0 V.

For a 100% efficient transformer, the primary winding has 1000 turns and the secondary 100 turns. If the power input to the above transformer is 1000 watts, the power output is_________.

In a transformer the resistance between its primary and secondary should be?

Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is?

The voltage transformation ratio of a transformer is equal to the ratio of?

The current in a 200 mH coil increases from 2 to 5 A in 0.1 Second. What is rate of change of current? A. 30 A/s B. 20 A/s C. 10 A/s D. none of these

If Voltage Standing Wave Ratio, (VSWR) of a wave is 2, its reflection coefficient will be _____.

In a full wave rectifier circuit using centre tapped transformer, the peak voltage across half of the secondary winding is 30 V. Then PIV is: (1) 30 V (2) 60 V (3) 15 V (4) 10 V

What will happen if the primary of a transformer is connected to D.C. supply?  (A) Transformer will operate with low efficiency (B) Transformer will operate with high efficiency (C) No effect (D) Transformer may start to smoke and burn

A large transformer operating at no load draws an exciting current Io of 5A, when the primary is connected to a 120 V, 60 Hz source. From a wattmeter test, it is known that iron losses are equal to 180 W. Calculate the reactive power absorbed by the core.  (A) 600 var (B) 572 var (C) 180 var (D) 360 var

The maximum flux in a transformer is φm when primary voltage is V and the frequency is f. If the primary voltage is 2 V and frequency is f/2, the flux will be (a) 4 φm (b) 0.25 φm (c) φm (d) 0.5 φm

Eddy current losses in transformer cores can be reduced by the use of  1. Solid cores  2. Laminated cores  3. Ferrites  Select the correct answer using the codes given below : (a) 2 and 3 only (b). 1 and 2 only (c) 1 and 3 only (d) 1, 2 and 3

The low voltage winding of a 400/230 V, 1-phase, 50 Hz transformer is to be connected to a 25 Hz, the supply voltage should be

In a 3-insulator string voltage distribution system the ratio of capacitance between pin and earth to the self capacitance of each unit is 1/4. If the potential across the top unit is 8 kV, then the string voltage is (A) 22.5 kV (B) 24 kV (C) 26 kV (D) 32.5 kV

For applications requiring speed ratio other than 2 : 1, the speed control of an induction motor can be effected by varying the number of stator poles employing  (1) multiple stator winding (2) pole amplitude modulation technique (3) consequent pole technique (4) Any of these

In a pure capacitive circuit if the supply frequency is reduced to 1/2, the current will?

In a pure inductive circuit if the supply frequency is reduced to 1/2, the current will?

The DFD is  (1) modern version of flowchart (2) mainly used at system specification stage (3) primary output of the system design phase (4) all of these

In a fullwave rectifier circuit with centre tap transformer, if voltage between one end of secondary winding and centre tap is 300V peak, then PIV (peak inverse voltage) is a. 300 V b. 150 V c. 600 V 5 d. 900 V

If a transformer primary is energised from a square wave voltage source, its output voltage will be a:  (A) square wave (B) sine wave (C) triangular wave (D) pulse wave

The turns ratio required to match an 80 ohms source to a 320 ohms load is? A.80 B.20 C.4 D.2