The commonly used materials for shielding or screening magnetism is

Step 1: Analyze the question We need a material that can shield (screen) a region from magnetic fields. This is called magnetic screening.

Step 2: The concept Magnetic field lines cannot be "blocked" the way light is. Instead, they are redirected. A material with very high magnetic permeability gives the field lines an easy path, so they pass through it rather than through the space it surrounds.

• Place a sensitive instrument (e.g., a watch or galvanometer) inside a hollow soft iron container.
• The field lines concentrate in the soft iron walls and go around the enclosed space.
• The space inside is therefore shielded from the external magnetic field.

Step 3: Check each option

• A. Aluminium: paramagnetic, very weak magnetic response. Not suitable.
• B. Brass: an alloy of copper and zinc, non-magnetic. Not suitable.
• C. Soft iron: very high permeability and easily magnetised and demagnetised. Ideal for shielding.
• D. Copper: diamagnetic, non-magnetic. Not suitable.

Step 4: Answer The correct option is C. Soft iron.

Tip: Remember "Soft iron = shield and core". Soft iron is used for magnetic screening, electromagnet cores and transformer cores because it magnetises and demagnetises easily. Hard steel is used for permanent magnets because it retains its magnetism.