Value of earth's magnetic field inside a metallic cage is:

Options

A. 1
B. 10
C. Zero
D. 2

Explanation

To solve the question regarding the value of Earth's magnetic field inside a metallic cage, we can follow these steps:

### Step 1: Understand the Concept of Magnetic Shielding
A metallic cage, often referred to as a Faraday cage, is designed to block external electric fields and magnetic fields. This is due to the properties of metals, which allow them to conduct electricity.

**Hint:** Consider how metals respond to external magnetic fields and how they can influence the magnetic field inside them.

### Step 2: Analyze the Properties of Metals
Metals have high magnetic permeability, which means they can easily become magnetized in the presence of an external magnetic field. When an external magnetic field is applied, the free electrons in the metal will move and create their own magnetic field that opposes the external field.

**Hint:** Think about how the movement of electrons in a conductor affects the magnetic field around it.

### Step 3: Apply the Concept to the Earth's Magnetic Field
When the Earth's magnetic field encounters the metallic cage, the induced magnetic field created by the movement of electrons in the metal will effectively cancel out the Earth's magnetic field inside the cage.

**Hint:** Reflect on the principle of superposition of magnetic fields and how opposing fields can lead to cancellation.

### Step 4: Conclude the Value of Earth's Magnetic Field Inside the Cage
Since the induced magnetic field inside the metallic cage cancels out the Earth's magnetic field, the resultant magnetic field inside the cage is zero.

**Hint:** Consider the implications of having a net magnetic field of zero in terms of magnetic field lines.

### Final Answer
The value of Earth's magnetic field inside a metallic cage is **zero**.