Question

If $L$ and $R$ be the inductance and resistance of the choke coil, then identify the correct statement.
A) $L$ is very high compared to $R$
B) $R$ is very high compared to $L$
C) Both $L$ and $R$ are high
D) Both $L$ and $R$ are low

Answer 1

- Hint: A choke coil allows DC signals while blocking AC signals. It behaves like an inductor to filter the unwanted AC signals. Resistance of a choke coil refers to the internal DC resistance of the coil.

Complete step-by-step solution
A choke coil is used in electric circuits to filter the unwanted AC currents. At the same time, it allows the passage of DC current. A choke coil chokes/blocks the higher frequencies while allowing lower frequencies to pass through it. Choke coils are made up of insulated wire wounds on a magnetic core and are used in most of the electronic devices today.
As mentioned, a choke coil filters high frequency AC currents. To do the filtration, a choke coil acts as an inductor. AC currents have high frequencies and always tend to change with time. When changing current is applied to a choke, it creates a magnetic field in it and blocks the changing current to pass through it. It is the inductance of the coil that blocks these high frequency signals. At the same time, DC currents, which do not change with time, are allowed to pass through it. This is how the filtration process works.
Resistance of a choke coil is also responsible for the passage of current through it. The internal DC resistance of an ideal choke is zero. This means that an ideal choke coil allows all the DC current coming to it, to pass through it, without any filtration. Internal DC resistance of a choke coil is one of the main criteria, which people look into, when they buy electronic devices which have choke coils. If a choke coil has low internal resistance, it is more effective.
In the question asked, $L$is the inductance and $R$ is the resistance of the choke coil. From the above explanation, it is clear that a good choke coil should have high inductance and low resistance. For an ideal choke coil, if $L$ and $R$ are compared, the value of $L$ will be more than the value of $R$. Therefore, option A is correct.

Note: In a choke coil, the magnetic core on which the insulated wire is wound is responsible for creating the magnetic field. The material used in the core determines the strength of the magnetic field and the inductance of the coil. Usually, to filter high frequencies, ferrite cores are used.