Magnetic effect of current practice · Mixed difficulty

A proton projected in a magnetic field of 0.020 T travels along a helical path of radius 5.0 cm and pitch 20 cm. Find the components of the velocity of the proton along and perpendicular to the magnetic field. Take the mass of the proton $=1.6 \times 10^{-27} \mathrm{~kg}$.

An ammeter reads upto 1 A. Its internal resistance is $0.81\,\,\Omega$. To increase the range to 10 A, the value of the required shunt is-

If a charged particle is projected with a velocity ' $v$ ' in a magnetic field ' $B$ ', then power developed by the field is

Which of the following statements is not true

In a current carrying long solenoid, the field produced does not depend upon

An electron flies into a homogeneous magnetic field of $10^{-3} \mathrm{~T}$ perpendicular to the force lines. The velocity of the electron is ${v}=4 \times 10^7 \mathrm{~m} \mathrm{~s}^{-1}$. What is the tangential acceleration of electron in the magnetic field?

Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): In an uniform magnetic field, speed and energy remains the same for a moving charged particle.
Reason (R): Moving charged particle experiences magnetic force perpendicular to its direction of motion.

An electron with mass $m$, velocity $v$ and charge $e$ describing half a revolution in a circle of radius $r$ in a magnetic field $B$, will experience change in energy equal to

Assertion (A) : A charged particle is moving in a circle with constant speed in uniform magnetic field. If we increase the speed of particle to twice, its acceleration will become four times.

Reason (R) : In circular path of radius $R$ with constant speed $v$, acceleration is given by $\frac{v^2}{R}$.

Three moving coil galvanometers are made of coils of three different material having torsional constant $1.8\,\, \times \,\,{10^{ - 8}},\,\,2.8\,\, \times \,\,{10^{ - 8}}$and $3.8\,\, \times \,\,{10^{ - 8}}$ respectively. If the three galvanometers are identical in all other respect, then in which of the above cases sensitivity is maximum?

There exists a uniform and constant magnetic field $B=1.67 T$ along positive $z$-axis. Simultaneously a proton and an alpha particle are projected from the origin with same speed $v=4 \sqrt{5} \times 10^5 \mathrm{~ms}^{-1}$ along positive and negative $x$-axis respectively. Find the separation between them when their velocities become mutually perpendicular for the first time. Ignore the force of interaction between them as well as any force other than magnetic force. Mass of the proton is $1.67 \times 10^{-27} \mathrm{~kg}$.

The coil of a moving coil galvanometer is wound over a metal frame in order to

A wire of length $L$ meter carrying a current of $I$ ampere is bent in the form of a circle. Its magnetic moment is:

A positively charged particle enters in a uniform magnetic field with uniform velocity $v$. If angle between velocity and magnetic field is $180^{\circ},$ the trajectory will be

A metal rod is moved with a constant velocity $v$ in a magnetic field. A potential difference appears across the two ends:

Assertion (A): Out of galvanometer, ammeter and voltmeter, resistance of ammeter is lowest and resistance of voltmeter is highest.

Reason (R): An ammeter is connected in series and a voltmeter is connected in parallel, in a circuit.

A particle of charge $q$ and mass $m$ starts moving from the origin under the action of an electric field, $E=E_0 \hat{{i}}$ and $B=B_0 \hat{{i}}$ with a velocity, $v=v_0 \hat{{j}}$. The speed of the particle will become $\frac{\sqrt{5}}{2} v_0$ after a time

A galvanometer has a resistance of $30\,\Omega$ and current of $2 \mathrm{~mA}$ is needed to give full scale deflection. What is the resistance needed and how is it to be connected to convert the galvanometer into voltmeter of 0.2 volt range.

A length of wire carries a steady current $i$. It is bent first to form a circular plane coil of one turn. The same length is now bent more sharply to give three loops of smaller radius. The magnetic field at the centre caused by the same current is

An electron is projected along the axis of
circular conductor carrying current I. Electron
will experience

Calculate the torque on a 100 turn rectangular coil of length $40 \mathrm{~cm}$ and breadth $20 \mathrm{~cm}$, carrying a current of $10 \mathrm{~A}$, when placed making an angle of $60^{\circ}$ with a magnetic field of $3 T$.

A charged particle with specific charge $s$ moves undeflected through a region of space containing mutually perpendicular and uniform electric and magnetic fields $E$ and $B$. When the electric field is switched off, the particle will move in a circular path of radius

The momentum of a charged particle moving in a perpendicular magnetic field depends on

The error in measuring the current with a tangent galvanometer is minimum when the deflection is about

Two long Straight wires each carrying an electric Current of $5 \mathrm{~A}$ are kept parallel to each other at a separation of $2.5 \mathrm{~cm}$. Find the magnitude of the magnetic force experiment by $10 \mathrm{~cm}$ of a wire.

A long straight wire with a circular cross-section having radius $R$, is carrying a steady current $I$. The current $I$ is uniformly distributed across this cross-section. Then the variation of magnetic field due to current $I$ with distance $r\,(r < R)$ from its centre will be

Assertion: Various regular polygons formed by a constant length current carrying wire, then magnetic induction at their centres are increases when their number of sides increases.
Reason: A magnetic dipole placed in non uniform magnetic field, then torque acting on it is always zero.

Magnetic moment for a solenoid and corresponding bar magnet is

A moving electric charge produces

A galvanometer has a resistance of $96\,\Omega$ and it is desired to pass $4 \%$ of the total current through it. Calculate the value of shunt resistance.