An electron 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
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 |
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?
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 |
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 (r < a) is and for (r > a) is , then is:
A solenoid of length 0.5 m has a radius of 1 cm and is made up of 500 turns. It carries a current of 5 A. What is the magnitude of the magnetic field inside the solenoid?
The horizontal component of the earth’s magnetic field at a certain place is \(3.0\times10^{-5}~\text{T}\) and the direction of the field is from the geographic south to the geographic north. A very long straight conductor is carrying a steady current of \(1~\text{A}\). What is the force per unit length on it when it is placed on a horizontal table and the direction of the current east to west?
1. \(3\times10^{-5}~\text{N m}^{-1}\)
2. \(2\times10^{-7}~\text{N m}^{-1}\)
3. zero
4. \(5\times10^{-7}~\text{N m}^{-1}\)
The horizontal component of the earth’s magnetic field at a certain place is 3.0 ×10–5 T and the direction of the field is from the geographic south to the geographic north. A very long straight conductor is carrying a steady current of 1 A. What is the force per unit length on it when it is placed on a horizontal table and the direction of the current is south to north?
A \(100\) turn closely wound circular coil of radius \(10~\text{cm}\) carries a current of \(3.2~\text{A}\). The magnetic field at the centre of the coil is:
1. \(4\times10^{-3}~\text{T}\)
2. \(6\times10^{-3}~\text{T}\)
3. \(2\times10^{-3}~\text{T}\)
4. \(5\times10^{-3}~\text{T}\)