1.Lõi thép máy biến áp được ghép từcác lá thép là để: (a) Giảm tổn hao công suất do dòng điện xoáy

(b) Giảm tổn hao công suất do từ trễ

(c) Giảm tổn hao công suất do dòng điện chạy qua dây quấn

(d) Giảm tất cảcác loại tổn hao công suất.

Option (c)

Explanation:

1.The transformer core is assembled from steel sheets to:

(a) Reduced power loss due to eddy current

(b) Reduced power loss due to hysteresis

(c) Reduced power loss due to current flowing through the winding

(d) Reduce all types of power loss.

A transformer is a device which converts the low voltage into high and vice  versa.

There are two types of a transformer.

Step up: It is used to convert low voltage into high.

Step down It is used to convert high voltage into high.

It depends on the number of turns in primary and the secondary coil.

The core of the transformer is laminated and it is in the form of sheets.

By using such type of core, the power loss due to the windings is reduced.

option (c) .

work: w = fd (given)

work done by chet   =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.