Why does a transformer require ac rather than dc? a. so that the magnetic field can be intensified b. so that the energy will be able to be transferred from one coil to another c. so that there will be enough voltage for transformation d. so that there will be a change in the magnetic field required for induction

Answer

Correct Answer is D ( so that there will be a change in the magnetic field required for induction)

Explanation:

Transformer is a device in which electrical energy is transferred  between two or more circuits.  

Transformer working is based on Faraday’s law of electromagnetic induction. Transformation action in a transformer occur due to mutual induction between two or more winding.

A transformer consists of one or more winding which are coupled magnetically and separated electrically with a magnetic core. A changing or varying current in one coil of the transformer produces a changing magnetic flux due to which an emf (electromotive force ) is induced across the second coil which is  wound around the same core.

Therefore a transformer needs an AC due to which a changing magnetic field will be created and due to this changing magnetic field an emf will induced in the second coil.

If DC is used in transformer then magnetic induction will not takes place since DC current will remain constant

the answer is f1 and d2 because if you put equal force on those two points the beam would balance trust me on this

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2