Solenoid and Bar Magnet

Q. The magnetism of magnet is due to

1. The spin motion of electron
2. Earth
3. Pressure of big magnet inside the earth
4. Cosmic rays

Q. The magnetic field lines due to a bar magnet are correctly shown in

1. 
2. 
3. 
4. 

Q. A bar magnet oscillates in a uniform magnetic field of magnitude B. The magnet is now cut along its magnetic axis into two equal parts and one of the part is again allowed to oscillate in a uniform magnetic field of magnitude 2B. The frequency of oscillation becomes

एक छड़ चुम्बक B परिमाण के एकसमान चुम्बकीय क्षेत्र में दोलन करती है। अब चुम्बक को इसके चुम्बकीय अक्ष के अनुदिश दो समान भागों में काटा जाता है तथा किसी एक भाग को 2B परिमाण के एकसमान चुम्बकीय क्षेत्र में पुनः दोलन कराया जाता है। दोलन की आवृत्ति हो जाती है

1. 2 times
   
   2 गुनी
2. 3 times
   
   3 गुनी
3. $\sqrt{2}\text{times}$
   
   $\sqrt{2}xquh$
4. 0.5 times
   
   0.5 गुनी

Q. A current loop placed in a magnetic field behaves like a

1. Magnetic dipole
2. Magnetic substance
3. Magnetic pole
4. All are true

Q. If a magnet of pole strength m is divided into four parts such that the length and width of each part is half that of initial one, then the pole strength of each part will be

1. $\frac{m}{4}$
   
2. $\frac{m}{2}$
   
3. $\frac{m}{8}$
   
4. $4m$

Q. A small bar magnet has a magnetic moment $1.2A-m^2$. The magnetic field at a distance 0.1 m on its axis will be: $({\mu }_0=4\pi \times {10}^{-7}T-m/A)$

1. $1.2\times {10}^{-4}T$
2. $2.4\times {10}^{-4}T$
3. $2.4\times {10}^{4}T$
4. $1.2\times {10}^{4}T$

Q. The magnetic field lines due to a bar magnet are correctly shown in

1. 
2. 
3. 
4.