87. An ideal transformer has 900 turns and 90 turns in its primary and secondary windings
respectively. If 220 V, 50 Hz AC is applied at its primary, What will be the AC available at its

secondary?
(A) 22V,5HZAC (B) 2.2 KV,50 HZ AC
(0) 22 ४, 50 HZ AC (D) 2.2 KV, 500 HZ AC

88. When connecting two or more transformers in parallel, a dead short circuit will be produced

in the secondary, if :

(A) _ the voltage ratio of the primaries and secondaries are not identical

(B) the transformers are not properly connected with regard to the polarity of primary
and secondary terminals

(C) the percentage impedance of the transformers are not equal in magnitude

(D) the kVA ratings of the transformers are different

89. The core of a transformer is laminated to reduce :

(A)
(C)

Hysterisis losses (8)
(0)

Copper losses

Saturation losses Eddy current losses

90. The primary and secondary voltages of an auto transformer are 600 V and 300 V
respectively. If the secondary current is 90 A, then the primary current is :

(A) 70A (B) 380A
(C) 45 ^ 0) 100A
91. ^ forward biased Silicon diode, will start to conduct when the applied voltage across it
reaches :
(A) 0.7V (8) 17
(© ۷ (D) 1.8 9४

92. Ifa source of light emits light equally in all directions, then the luminance at any point on a
plane perpendicular to the line joining the point and the source 18 :

(^) directly proportional to the square of the distance between the source and the
plane
(2) inversely proportional to the square of the distance between the source and the
plane
(C) directly proportional to the distance between the source and the plane
(D) inversely proportional to the distance between the source and the plane
93. The type of lamp in which gas or vapour is made luminous by an electric discharge through
them is :
(A) Halogen lamp ൯) Incandescent lamp
(C) LED lamp (D) Discharge lamp
A 13 121/2021

[7.7.0.]