- 1(current)
Q. No.A current \(i\) flows through a semi-circular loop of radius \(r,\) attached to two long straight wires along the open diameter of the loop. The magnetic field at the centre of the loop is:
| 1. | \(\dfrac{\mu_0i}{4r}\) |
| 2. | \(\dfrac{\mu_0i}{4r}+\dfrac{\mu_0i}{2\pi r}\) |
| 3. | \(\dfrac{\mu_0i}{4r}+\dfrac{\mu_0i}{4\pi r}\) |
| 4. | \(\left[\left(\dfrac{\mu_0i}{4r}\right)^2+\left(\dfrac{\mu_0i}{4\pi r}\right)^2\right]^{\frac12} \) |
Subtopic: Â Magnetic Field due to various cases |
 84%
Level 1: 80%+
Hints
The shape of the magnetic field lines due to an infinite long, straight current carrying conductor is:
| 1. | a straight line | 2. | circular |
| 3. | elliptical | 4. | a plane |
Subtopic: Â Magnetic Field due to various cases |
 73%
Level 2: 60%+
NEET - 2022
Hints
The magnetic field at a point (\(P\)) on the axis of a circular current-carrying wire is \(\dfrac18\) of the field at its centre. The radius of the circular curve is \(R.\) The distance between \(P\) and the centre of the circle \((OP)\) is:
Then:
Then:
| 1. | \(OP=R\) | 2. | \(OP=\dfrac R2\) |
| 3. | \(OP=\sqrt3R \) | 4. | \(OP=8R\) |
Subtopic: Â Magnetic Field due to various cases |
 75%
Level 2: 60%+
Hints
Two long parallel wires carrying currents \(I_1\) and \(I_2\) give a magnetic field of \(3\) G at a point exactly mid-way between the two wires. When one of the currents is reversed, the field becomes \(5\) G. The ratio of the large current to the smaller one is:
| 1. | \(2\) | 2. | \(\dfrac43\) |
| 3. | \(\dfrac32\) | 4. | \(4\) |
Subtopic: Â Magnetic Field due to various cases |
 75%
Level 2: 60%+
Hints
A long solenoid of radius \(1~\text{mm}\) has \(100\) turns per mm. If \(1~\text{A}\) current flows in the solenoid, the magnetic field strength at the centre of the solenoid is:
| 1. | \(6.28 \times 10^{-4} ~\text{T} \) | 2. | \(6.28 \times 10^{-2}~\text{T}\) |
| 3. | \(12.56 \times 10^{-2}~\text{T}\) | 4. | \(12.56 \times 10^{-4} ~\text{T}\) |
Subtopic: Â Magnetic Field due to various cases |
 65%
Level 2: 60%+
NEET - 2022
Hints
A long solenoid has a square cross-section of side \(a\). It has turn-density n (number of turns per unit axial length). A current \(i\) is passed through this solenoid. The magnetic field at the centre of the solenoid is \(B_c\). Then, \(B_c\) is proportional to:
(I) \(a\)
(II) \( \dfrac{1} {a}\)
(III) \(n\)
(IV) \(i\)
Choose the correct option from the given ones:
1. I, III, IV
2. II, III, IV
3. III, IV
4. IV Only
(I) \(a\)
(II) \( \dfrac{1} {a}\)
(III) \(n\)
(IV) \(i\)
Choose the correct option from the given ones:
1. I, III, IV
2. II, III, IV
3. III, IV
4. IV Only
Subtopic: Â Magnetic Field due to various cases |
 72%
Level 2: 60%+
Hints
- 1(current)
Q. No.
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