A beam of cathode rays is subjected to crossed Electric (E) and magnetic fields(B). The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by:

1. B22VE2                                             

2. 2VB2E2

3. 2VE2B2                                           

4. E22VB2

(where V is the potential difference between cathode and anode)

Subtopic:  Lorentz Force |
 58%
From NCERT
NEET - 2010
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A galvanometer has a coil of resistance 100Ω and gives a full scale deflection for 30 mA current.If it is to work as a voltmeter of 30V range, the resistance required to be added will be 

(1) 900 Ω                                     

(2) 1800 Ω

(3) 500 Ω                                     

(4) 1000 Ω

Subtopic:  Conversion to Ammeter & Voltmeter |
 80%
From NCERT
NEET - 2010
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A square current carrying loop is suspended in a uniform magnetic field acting in the plane of the loop. If the force on one arm of the loop is F, the net force on the remaining three arms of the loop is

1. 3F                 

2. -F

3. -3F               

4.  F

Subtopic:  Current Carrying Loop: Force & Torque |
 83%
From NCERT
NEET - 2010
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A current loop consists of two identical semicircular parts each of radius \(R\), one lying in the x-y plane, and the other in the x-z plane. If the current in the loop is \(i\), what will be the resultant magnetic field due to the two semicircular parts at their common centre?

1. \( \frac{\mu_0 i}{2 \sqrt{2} R} \) 2. \( \frac{\mu_0 i}{2 R} \)
3. \( \frac{\mu_0 i}{4 R} \) 4. \( \frac{\mu_0 i}{\sqrt{2} R}\)

Subtopic:  Magnetic Field due to various cases |
 65%
From NCERT
NEET - 2010
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A closely wound solenoid of 2000 turns and area of cross-section 1.5×10-4 m2 carries a current of 2.0 A. It is suspended through its centre and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field 5×10-2 T making an angle of 30° with the axis of the solenoid. The torque on the solenoid will be

(1) 3×10-3 Nm                                 

(2) 1.5×10-3 Nm

(3) 1.5×10-2 Nm                               

(4) 3×10-2 Nm

Subtopic:  Magnetic Moment |
 73%
From NCERT
NEET - 2010
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A particle having a mass of 10-2 kg carries a charge of 5×10-8 C. The particle is given an initial horizontal velocity of 105 ms-1 in the presence of electric field E and magnetic field B. To keep the particle moving in a horizontal direction, it is necessary that

(1) B should be perpendicular to the direction of velocity and E should be along the direction of velocity.

(2) Both B and E should be along the direction of velocity.

(3) Both B and E are mutually perpendicular and perpendicular to the direction of velocity.

(4) B should be along the direction of velocity and E should be perpendicular to the direction of velocity.

Which one of the following pairs of statements are possible?

1.   (1) and (3)                                       2.    (3) and (4)

3.   (2) and (3)                                       4.   (2) and (4)

Subtopic:  Lorentz Force |
 54%
From NCERT
NEET - 2010
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Under the influence of a uniform magnetic field, a charged particle moves with constant speed v in a circle of radius R. The time period of rotation of the particle -

1. depends on v and not on R

2. depends on R and not on v

3. is independent of both v and R

4. depends on both v and R

Subtopic:  Lorentz Force |
 82%
From NCERT
NEET - 2009
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The magnetic force acting on a charged particle of charge -2μC in a magnetic field of 2T acting in y-direction, when the particle velocity is 2i^+3j^×106 ms-1 is.

1. 8 N in -z-direction

2. 4 N in z-direction

3. 8 N in y-direction

4. 4 N in y-direction

Subtopic:  Lorentz Force |
 69%
From NCERT
NEET - 2009
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A galvanometer having a coil resistance of 60Ω shows full scale deflection when a current of 1.0A passes through it. It can be converted into an ammeter to read currents upto 5.0A by 

(a) putting in series resistance of 240Ω

(b) putting in parallel resistance of 240Ω

(c) putting in series resistance of 15Ω

(d) putting in parallel resistance of 15Ω

Subtopic:  Conversion to Ammeter & Voltmeter |
 76%
From NCERT
NEET - 2009
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A closed-loop PQRS carrying a current is placed in a uniform magnetic field. If the magnetic forces on segments PS, SR and RO are F1, F2 and F3 respectively and are in the plane of the paper and along with the directions shown the force on the segment QP is 

(a)F3+F1-F2

(b)F3-F12+F22

(c)F3-F12-F22

(d)F3-F1+F2

Subtopic:  Current Carrying Loop: Force & Torque |
 78%
From NCERT
NEET - 2008
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