Magnetic Effects of Current - NEET Physics Questions
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Magnetic Effects of Current

Question 71: moderate

An eΘ is moving in a zero gravity region towards upward direction & magnetic field in this region is along east direction. Then what will be the direction of electric field in this region so that eΘ can remain undeflected :

1. North
2. South
3. East
4. West
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Question 72: moderate

The acceleration of an eΘ at a certain moment in a magnetic field

\[\overrightarrow{B}=2\hat{i}+3\hat{j}+4\hat{k}\] is

\[\overrightarrow{a}=x\hat{i}+\hat{j}-\hat{k}\] .

The value of x is :

1. 0.5
2. 1
3. 2.5
4. 1.5
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Question 73: moderate

Radius of the current carrying coil is R. If magnetic field at any point on the axis of the coil is \[Bx=\frac{B_{0}}{64}\] then find out axial distance of this point :

1. √3 R
2. √5 R
3. √15 R
4. R
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Question 74: easy

A ring of radius r is carrying a current I. The magnetic field B is always perpendicular to the ring as shown in Fig. The force on the ring is :

1. 2 I r B
2. I r B
3. zero
4. 2 π r IB
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Question 75: moderate

Three long, straight and parallel wires carrying currents are arranged as shown in figure. The force experienced by 10 cm length of wire Q is :

1. \[1.4\times 10^{-4}N towards the right\]
2. \[1.4\times 10^{-4}N towards left\]
3. \[2.6\times 10^{-4}N to the right\]
4. \[2.6\times 10^{-4}N to the left\]
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Question 76: moderate

A current carrying loop is placed in a uniform magnetic field in four different orientations, I, II, III & IV arrange them in the decreasing order of potential Energy :

1. I > III > II > IV
2. I > II > III > IV
3. I > IV > II > III
4. III > IV > I > II
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Question 77: moderate

Two bar magnets with magnetic moments 2M and M are fastened together at right angles to each other at their centres to form a crossed system, which can rotate freely about a vertical axis through the centre. The crossed system sets in earth’s magnetic field with magnet having magnetic moment 2M making and angle θ with the magnetic meridian such that :

1. \[\theta=tan^{-1}\left( \frac{1}{\sqrt{3}} \right)\]
2. \[\theta=tan^{-1}\left( \sqrt{3} \right)\]
3. \[\theta=tan^{-1}\left( \frac{1}{{2}} \right)\]
4. \[\theta=tan^{-1}\left( \frac{3}{{4}} \right)\]
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Question 78: moderate

Time period for a magnet is T. If it is divided in four equal parts along its axis and perpendicular to its axis as shown then time period for each part will be :

1. 4 T
2. T/4
3. T/2
4. T
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Question 79: moderate

A wire carrying a current i is placed in a uniform magnetic field in the form of the curve
y =a sin (πx/L), 0 ≤ x ≤ 2L. The force acting on the wire is :

1. iBL/π
2. iBLπ
3. 2iBL
4. zero
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Question 80: moderate

Same current i = 2A is flowing in a wire frame as shown in figure. The frame is a combination of two equilateral triangles ACD and CDE of side 1m. It is placed in uniform magnetic field B = 4T acting perpendicular to the plane of frame. The magnitude of magnetic force acting on the frame is :

1. 24 N
2. Zero
3. 16 N
4. 8 N
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