Q1. When a resistance is to be transferred from primary to secondary side of transformer with the turns ratio as k, it must be

a. Multiplied by k ∧ 2
b. Multiplied by k
c. Divided by k
d. Divided by k ∧ 2

ANSWER: a. Multiplied by k ∧ 2

Q2. If the power factor of load is near unity and leading, the full load voltage regulation of a power transformer will be

a. Zero
b. One
c. 0.5
d. O.707

Q3. If the applied voltage of a certain transformer is increased by 50% keeping the frequency constant, the maximum flux density will become

a. Remains same
b. 1.5 times the original value
c. Double the original value
d. Half of the original value

ANSWER: b. 1.5 times the original value

Q4. A 10 kVA, 2000 / 100v transformer has R1=1.5 ohm, R2=0.005 ohm, X1=2.5 ohm and X2=0.08 ohm. The equivalent resistance referred to primary is

a. 3 ohm
b. 3.25 ohm
c. 3.5 ohm
d. 3.8 ohm

Q5. A transformer when connected to a 230V, 50Hz supply, under no load draws a current of 4A at a power factor of 0.2 lagging. The magnetizing current (Im) and core loss (Pc) is equal to

a. 3.919A, 184W
b. 1.84A, 391.9W
c. 39.19A, 184W
d. 3A, 180W

Q6. If the supply voltage is kept at constant value and the supply frequency is increased. The magnetizing and core loss component

a. Both will decrease
b. Magnetizing component will increase and core loss will decrease
c. Magnetizing component will decrease and core loss will increase
d. Both will increase