How to Calculate Currents in a Simple Transformer?

In summary, the conversation discusses a simple transformer with negligible losses, where the primary coil has 2000 turns and the secondary coil has 150 turns. An AC current of 240Vrms is applied to the primary and the secondary is connected to a resistor of 300 ohms. The conversation then calculates the secondary current to be 0.06A and the primary current to be 0.0045A, with a power output of 1.08 watts.
  • #1
mogley76
19
0

Homework Statement



A simple transformer with negligable looses has a primary coil of 2000 turns and a secondary coil of 150 turns. if an AC current of 240Vrms is applied to the primary, calculate the secondary and primary currents if the secondary is connected across a resistor of 300 ohms.

Homework Equations


none given


The Attempt at a Solution



i Know this much : vs/vp = Ns/Np
so..
150/2000 * 240 = 18vrms which is vs
then v=ir so
Is = 18/300 : 0.06A
Ip = 240/300 : 0.08A

is all this right or am i horribaly wrong?
 
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  • #2


The resistor is in the secondary circuit, not the primary, so you can't just divide the primary voltage by that value to find the primary current.

What you can do is recognize that the power delivered to the resistor in the secondary must ultimately be coming from the primary current source, and if there are no losses in the transformer, then the power should balance on both sides.
 
  • #3


so secondary wattage= Is * Vs : .06A*18Vrms which is 1.08 w
and primary current = 1.08/primary vrms of 240 which is 4.5E-3 A?
 
  • #4


Looks reasonable. You might convert your current values to mA for clarity.
 
  • #5


great! thanks!
 

Related to How to Calculate Currents in a Simple Transformer?

1. What are Transformers and how do they work?

Transformers are devices that are used to transfer electrical energy from one circuit to another through the principle of electromagnetic induction. They work by using two coils of wire, known as the primary and secondary coils, which are wrapped around a metal core. When an alternating current (AC) flows through the primary coil, it creates a changing magnetic field around the core. This magnetic field induces a voltage in the secondary coil, allowing energy to be transferred from the primary circuit to the secondary circuit.

2. What are the main components of a Transformer?

The main components of a Transformer include a primary coil, a secondary coil, and a metal core. The primary coil is connected to the input voltage source and is responsible for creating a changing magnetic field. The secondary coil is connected to the output load and receives the induced voltage from the primary coil. The metal core, typically made of iron or steel, is used to increase the efficiency of energy transfer by concentrating and directing the magnetic field.

3. What are the different types of Transformers?

There are two main types of Transformers: step-up transformers and step-down transformers. Step-up transformers have a higher number of turns in the secondary coil than in the primary coil, resulting in an output voltage that is greater than the input voltage. These types of Transformers are used to increase the voltage for long-distance transmission of electricity. Step-down transformers have a lower number of turns in the secondary coil, resulting in an output voltage that is lower than the input voltage. These types of Transformers are used to decrease the voltage for household and industrial use.

4. What are the applications of Transformers?

Transformers have various applications in everyday life and various industries. They are used in power grids to transfer electricity from power plants to homes and businesses. They are also used in electronic devices, such as chargers, to convert high voltage to low voltage. In the industrial sector, Transformers are used to control and regulate the voltage in machinery and equipment. They are also used in medical equipment, such as MRI machines, and in renewable energy sources, such as wind turbines and solar panels.

5. What are the safety precautions when working with Transformers?

When working with Transformers, it is important to ensure that the power is turned off and the device is unplugged before handling it. It is also essential to wear protective gear, such as gloves and safety glasses, as Transformers can have high voltage and can cause electric shock. Transformers should also be regularly inspected and maintained to prevent any malfunctions or accidents. If any damage or issues are found, a professional should be consulted for repairs or replacements.

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