A long solenoid carrying a current produces a magnetic field \(B\) along its axis.
If the current is doubled and the number of turns per cm is halved, what will be the new value of the magnetic field?
1. \(B/2\)
2. \(B\)
3. \(2B\)
4. \(4B\)
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. | \(5.4\times 10^{-8}~\text{T}\) |
1. | \(0\) | 2. | \(1.2\times 10^{-4}~\text{T}\) |
3. | \(2.1\times 10^{-4}~\text{T}\) | 4. | None of these |
What properties will a galvanometer that is acting as a voltmeter have?
1. | high resistance in series with its coil | 2. | low resistance in parallel with its coil |
3. | low resistance in series with its coil | 4. | high resistance in parallel with its coil |
1. | \({G \over (S+G)}\) | 2. | \({S^2 \over (S+G)}\) |
3. | \({SG \over (S+G)}\) | 4. | \({G^2 \over (S+G)}\) |
(a) | \(\oint B\cdot dl= \mp 2\mu_0 I\) |
(b) | the value of \(\oint B\cdot dl\) is independent of the sense of \(C\). |
(c) | there may be a point on \(C\) where \(B\) and \(dl\) are perpendicular. |
(d) | \(B\) vanishes everywhere on \(C\). |
Which of the above statements are correct?
1. (a) and (b)
2. (a) and (c)
3. (b) and (c)
4. (c) and (d)
A square loop with a side \(l\) is held in a uniform magnetic field \(B\), such that its plane making an angle \(\alpha\) with \(B\). A current \(i\) flows through the loop. What will be the torque experienced by the loop in this position?
1. \(Bil^{2}\)
2. \(Bil^{2} \sinα\)
3. \(Bil^{2} \cosα\)
4. zero