Magnetic effect of current practice · Medium

A galvanometer having 30 divisions has a current sensitivity of $20 \mu \mathrm{A} /$division. It has a resistance of $20\,\Omega$. How will you convert it into an ammeter measuring upto 1 ampere? How will you convert this ammeter into voltmeter reading upto 1 volt?

At what distance from a long straight wire carrying a current of $12 \mathrm{~A}$ will the magnetic field be equal to $3 \times 10^{-5} \mathrm{~Wb} / \mathrm{m}^2$ ?

Before using the tangent galvanometer, its coil
is set up in

A straight wire of mass $200 \mathrm{~g}$ and length $1.5 \mathrm{~m}$ carries a current of $2 \mathrm{~A}$. It is suspended in midair by a uniform horizontal magnetic field $B$. The magnitude of $B$ (in tesla) is (assume $\mathrm{g}=9.8 \mathrm{~ms}^{-2}$ )

A closely wound flat circular coil of 25 turns of wire has diameter of $10 \mathrm{~cm}$ which carries current of $4 \mathrm{~A}$, the flux density at the centre of a coil will be

Magnetic induction at the centre of a current carrying circular loop of area $\pi$ square metre is 0.2 Tesla. The magnetic moment of the loop is $\left(\mu_0\right.$ is the permeability of air)

The resistance of an ideal voltmeter is

The cyclotron assembly is filled with

The dominant force experienced by an electron
moving in a wire is

Force $\vec{F}$ experienced by a charger $q$ moving with a velocity $\vec{v}$ in an electric field of strength $\overrightarrow{\mathrm{E}}$ and a magnetic field of strength $\overrightarrow{\mathrm{B}}$ is:

A proton is revolving in a circular path with constant speed. Angle between angular momentum and magnetic dipole moment associated with it is

A charged particle moves along a circle under the action of possible constant electric and magnetic fields. Which of the following are possible?

A proton and an $\alpha -$ particle enter a uniform magnetic field perpendicularly with the same speed. If proton takes $25\,\mu$ second to make 5 revolutions, then the time period for the $\alpha -$ particle would be

A charge is fired through a magnetic field. The force acting on it is maximum when the direction of motion of the charge and magnetic field is

The magnetic dipole moment of a current loop
is independent of :

The sensitivity of a tangent galvanometer is increased if

A cyclotron is used to accelerate protons $\left({ }_1^1 {H}\right)$ deuterons $\left({ }_1^2 \mathrm{H}\right)$ and $\alpha$-particles $\left({ }_2^4 \mathrm{He}\right)$. While exiting under similar conditions, the minimum $\mathrm{KE}$ is gained by :

The magnetic field is absent in which one of the
following physical situation?

If the acceleration and velocity of a charged particle moving in a constant magnetic region is given by $\mathbf{a}=a_1 \hat{\mathbf{i}}+a_2 \hat{\mathbf{k}}, \mathbf{v}=b_1 \hat{\mathbf{i}}+b_2 \hat{\mathbf{k}}$. $\left[a_1, a_2, b_1\right.$ and $b_2$ are constants], then choose the wrong statement.

Statement (I): A uniform electric field and a
uniform magnetic field are pointed in the same
direction. If an electron is projected in the same
direction the electron velocity will decrease in
magnitude.
Statement (II): Two infinite long parallel wires
are carrying current in the same direction. The
magnetic field at a point midway between the wires
is zero.
Statement (III): No net force acts on a rectangular
coil carrying a steady current when suspended in
a uniform magnetic field.
Which of the following is correct?

The magnitude of the magnetic field inside a
long solenoid is increased by

Assertion: A charge, whether stationary or in
motion produces a magnetic field around it
Reason: Moving charges produce only electric
field in the surrounding space.

The instantaneous acceleration of an electron in a magnetic field $\bar{B}=2 \bar{i}+3 \bar{j}+4 \bar{k}$ is $\bar{a}=x \bar{i}+\bar{j}-\bar{k}$. The magnitude of acceleration is

When a charge particle moving with velocity $\overrightarrow{\mathbf{v}}$ is subjected to a magnetic field of induction $\vec{B}$, the force on it is non-zero. This implies that

Assertion (A): If a point charge $q$ is placed in front of a infinite ground conducting plane surface, the point charge will experience a force.
Reason (R): This force is due to the induced charge on the conducting surface which is at zero potential.

A current carrying coil placed in a magnetic field $B$ experiences a torque $\tau$. If $\theta$ is the angle between the normal to the plane of the coil and field $B$ and $\varphi$ is the flux linked with the coil, then

A solenoid is $1.0 \mathrm{~m}$ long and $3.0 \mathrm{~cm}$ in diameter. It has five layers of windings of 850 turns each and carries a current of $5.0 \mathrm{~A}$. What is $B$ at its centre ?

A moving coil galvanometer A has 200 turns and resistance $100\,\,\Omega$. Another meter B has 100 turns and resistance $40\,\,\Omega$. All the other quantities are same in both the cases. The current sensitivity of the galvanometer is

Assertion: An electron and proton enters a magnetic field with equal velocities, then, the force experienced by the proton will be more than electron.

Reason: The mass of proton is 1837 times more than electron.

A vertical rectangular coil of sides $5\,cm \times 2\,cm$ has 10 turns and carries a current of $2\,A$. The torque (couple) on the coil when it is placed in a uniform horizontal magnetic field of $0.1\,\,T$ with its plane perpendicular to the field is