A long solenoid is formed by winding turns cm. If A current flows, then the magnetic field produced inside the solenoid is . ( T m A)

Question

A long solenoid is formed by winding  turns cm. If  A current flows, then the magnetic field produced inside the solenoid is . ( T m A)

Canvas Classes · Accepted Answer

🧠 Straight Plug-In: , Mind the "per cm"

The field deep inside a long solenoid is , where  is turns per metre. The only care needed is converting " turns cm" into per-metre units. After that it is direct substitution.

The clue: "long solenoid" plus turns-per-length tells you immediately to use .

🗺️ Working It Out

Convert the turn density: .

Now the field, with  and  A:

Using :

That is option (b).

⚡ The Smart Move

Group the powers of ten before multiplying : , so . Then one multip

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