Q1: A step-up transformer has 80 turns on its primary coil and 1200 turns on its secondary coil. The
primary circuit is supplied with an alternating current at 120 V.
a) What voltage is being applied across the secondary circuit?
b) The current in the secondary circuit is 2.0 A. What current is in the primary circuit?
c) What are the power input and output of the transformer?

Respuesta :

Answer:

a. 1.8 kV b. 30 A c. power input = 3.6 kW, power output = 3.6 kW

Explanation:

a. Since turns ratio N₁/N₂  = V₁/V₂ where N₁ = number of turns of primary coil = 80 turns, N₂ = number of turns of secondary coil = 1200 turns, V₁ = voltage in primary circuit = 120 V and V₂ = voltage in secondary circuit = unknown

So, V₂ = N₂V₁/N₁

= 1200 × 120 V/80

= 1800 V

= 1.8 kV

b. Also, N₁/N₂ = I₂/I₁ where I₁ = current in primary circuit = unknown and I₂ =  current in secondary circuit = 2.0 A

So, I₁ = N₂I₂/N₁

= 1200 × 2.0 A/80

= 30 A

c. The power input of the transformer P₁ = I₁V₁

= 30 A × 120 V

= 3600 W

= 3.6 kW

The power output of the transformer P₂ = I₂V₂

= 2 A × 1800 V

= 3600 W

= 3.6 kW

a) The voltage applied across the secondary circuit is 1.8 kV

b) The current in the primary circuit is  30 A

c) The power input and output of the transformer are 3.6 kW and 3.6 kW.

What is transformer?

A transformer transfers electric energy from one AC circuit to one or more other circuits, either stepping up or stepping down the voltage.

a)  Turns ratio N₁/N₂  = V₁/V₂ where N₁ = number of turns of primary coil = 80 turns, N₂ = number of turns of secondary coil = 1200 turns, V₁ = voltage in primary circuit = 120 V

Substitute the values and we get the voltage in secondary circuit is

V₂ = N₂V₁/N₁

V₂ = 1200 × 120 V/80

V₂ = 1800 V

V₂ = 1.8 kV

Thus, the voltage applied across the secondary circuit is 1.8 kV

b) Turn ratio also represented as  N₁/N₂ = I₂/I₁ where  I₂ is the current in secondary circuit = 2.0 A
Put the values, we have current in primary circuit is

I₁ = N₂I₂/N₁

I₁ = 1200 × 2.0 A/80

I₁ = 30 A

Thus, the current in the primary circuit is  30 A

c) The power input of the transformer P₁ = I₁V₁

P₁ = 30 A × 120 V

P₁ = 3600 W

P₁ = 3.6 kW

The power output of the transformer P₂ = I₂V₂

P₂= 2 A × 1800 V

P₂= 3600 W

P₂= 3.6 kW

The power input and output of the transformer are 3.6 kW and 3.6 kW.

Learn more about transformer.

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