Understanding Transformer Frequency

Transformers are essential devices used in electrical systems to change voltage levels. A key characteristic of a transformer is how it handles the frequency of the alternating current (AC) supply.

Transformer Principle and Frequency

The frequency of the electrical supply is determined by the source generating the AC power. When this AC supply is fed into the primary coil of a transformer, it creates a changing magnetic field within the transformer's core.

• This changing magnetic field is what induces a voltage in the secondary coil.
• Crucially, the rate at which this magnetic field changes is directly dependent on the frequency of the input supply.
• Therefore, the frequency of the voltage induced in the secondary coil is exactly the same as the frequency of the primary supply.

Analysis of the Question

The question provides the following information:

• Primary to secondary turns ratio: 1:2
• Primary supply frequency: 50 Hz

The turns ratio (often denoted as $N_p : N_s$, where $N_p$ is the number of turns in the primary coil and $N_s$ is the number of turns in the secondary coil) affects the voltage and current transformation according to the following relationships:

• Voltage ratio: $\frac{V_p}{V_s} = \frac{N_p}{N_s}$
• Current ratio: $\frac{I_s}{I_p} = \frac{N_p}{N_s}$

In this specific case, the ratio $\frac{N_p}{N_s} = \frac{1}{2}$. This means the secondary voltage will be twice the primary voltage, and the secondary current will be half the primary current (assuming an ideal transformer).

However, the frequency is independent of the turns ratio. The frequency of the secondary supply remains unchanged from the primary supply frequency.

Determining Secondary Frequency

Given that the primary supply frequency is 50 Hz, and the frequency does not change as it passes through the transformer:

• Primary Frequency ($f_p$) = 50 Hz
• Secondary Frequency ($f_s$) = Primary Frequency ($f_p$)
• Therefore, $f_s$ = 50 Hz

Looking at the options provided:

• Options 1 and 2 suggest the frequency changes based on multiplication.
• Option 3 suggests the frequency is halved.
• Option 4 correctly states the frequency remains 50 Hz.

Thus, the frequency of the secondary supply is the same as the primary supply frequency.