A straight wire of mass \(200~\text{g}\) and length \(1.5~\text{m}\) carries a current of \(2~\text{A}\). It is suspended in mid-air by a uniform horizontal magnetic field \(B\) (shown in the figure). What is the magnitude of the magnetic field?

       

1. \(0.65~\text{T}\) 2. \(0.77~\text{T}\)
3. \(0.44~\text{T}\) 4. \(0.20~\text{T}\)
Subtopic:  Lorentz Force |
 81%
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In a region of space, magnetic field is parallel to the positive \(y\text-\)axis and the charged particle is moving along the positive \(x\text-\)axis (as shown in the figure). The directions of Lorentz force for an electron (negative charge) and proton (positive charge) are respectively:

  

1. \(-z\text-\)axis, \(+z\text-\)axis 2. \(+z\text-\)axis, \(-z\text-\)axis
3. \(-z\text-\)axis, \(-z\text-\)axis 4. \(+z\text-\)axis, \(+z\text-\)axis
Subtopic:  Lorentz Force |
 63%
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The radius of the path of an electron and frequency (mass 9×10-31 kg and charge 1.6×10-19 C) moving at a speed of \(3\times10^7\) m/s in a magnetic field of \(6\times10^{-4}\) T perpendicular to it are respectively:
1. \(24\) cm, \(4\) MHz

2. \(22\) cm, \(4\) MHz

3. \(28\) cm, \(2\) MHz

4. \(26\) cm, \(2\) MHz

Subtopic:  Lorentz Force |
 72%
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An electron mass 9×10-31 kg and charge 1.6×10-19 C is moving at a speed of 3 ×107 m/s in a magnetic field perpendicular to it. The energy of the electron in keV is: ( 1 eV = 1.6 × 10–19 J)

1. 2.5 keV

2. 3.5 keV

3. 20 keV

4. 3.0 keV

Subtopic:  Lorentz Force |
 62%
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An element \(\Delta l=\Delta x \hat{i}\) is placed at the origin and carries a large current of \(I=10\) A (as shown in the figure). What is the magnetic field on the \(y\text-\)axis at a distance of \(0.5\) m? \((\Delta x=1~\text{cm})\)

 1. \(6\times 10^{-8}~\text{T}\) 2. \(4\times 10^{-8}~\text{T}\)
3. \(5\times 10^{-8}~\text{T}\) 4. \(5.4\times 10^{-8}~\text{T}\)
Subtopic:  Biot-Savart Law |
 80%
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A straight wire carrying a current of \(12\) A is bent into a semi-circular arc of radius \(2.0\) cm as shown in the figure. Considering the magnetic field \(B\) at the centre of the arc, what will be the magnetic field due to the straight segments?

1. \(0\) 2. \(1.2\times 10^{-4}~\text{T}\)
3. \(2.1\times 10^{-4}~\text{T}\) 4. None of these
Subtopic:  Biot-Savart Law |
 79%
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A straight wire carrying a current of 12 A is bent into a semi-circular arc of radius 2.0 cm as shown in the figure. Consider the magnetic field B at the centre of the arc. What is the magnetic field at centre due to the semi-circular loop?

 

1. 0
2. 3.8×10-4 T
3. 1.9×10-4 T
4. 2.9×10-4 T

Subtopic:  Biot-Savart Law |
 66%
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Consider a tightly wound \(100\) turn coil of radius \(10\) cm, carrying a current of \(1\) A. What is the magnitude of the magnetic field at the centre of the coil?

1. \(8.2\times10^{-4}\) T 2. \(4.6\times10^{-4}\) T
3. \(5.2\times10^{-4}\) T 4. \(6.2\times10^{-4}\) T
Subtopic:  Magnetic Field due to various cases |
 78%
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The figure shows a long straight wire of a circular cross-section (radius a) carrying steady current I. The current I is uniformly distributed across this cross-section. If the magnetic field in the region (a) is B1 and for (a) is B2, then B1B2 is:

1. ar
2. a2r2
3. r2a2
4. ra

Subtopic:  Magnetic Field due to various cases |
 51%
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A solenoid of length \(0.5~\text m\) has a radius of \(1~\text{cm}\) and is made up of \(500\) turns. It carries a current of \(5~\text A.\) What is the magnitude of the magnetic field inside the solenoid?
1. \(6.28\times 10^{-3}~\text T\)
2. \(3.14\times 10^{-3}~\text T\)
3. \(2.72\times 10^{-3}~\text T\)
4. \(5.17\times 10^{-3}~\text T\)

Subtopic:  Magnetic Field due to various cases |
 74%
From NCERT
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