The Circular Motion

Q. An uniformly charged thin ring has radius $10\text{cm}$ and total charge $12\text{nC}$. An electron is placed on the ring's axis at a distance $25\text{cm}$ from the centre of the ring and is constrained to stay on the axis of ring. The electron is then released from rest. Find the speed of electron when it reaches the center of the ring.

1. $$20\times {10}^4\text{m/s}$$
2. $$1.5\times {10}^4\text{m/s}$$
3. $$18\times {10}^5\text{m/s}$$
4. $$15.45\times {10}^6\text{m/s}$$

Q. What is the angle between plane of eddy currents and the plane of magnetic field?

1. ${60}^{\circ }$
2. ${90}^{\circ }$
3. ${180}^{\circ }$
4. $0^{\circ }$

Q. Copper of fixed volume V is drawn into wire of length l. When this wire is subjected to constqnt force f , the extension produced in wire is △ l. which of th following graphs is a straight line? 1. △ l vs 1/l (2.) △ l vs l

Q. A proton and an alpha particle both enter a region of uniform magnetic field $B$, moving at right angles to the field $B$. If the radius of circular orbits for both the particles is equal and the kinetic energy of the proton is $1MeV$, the energy of the alpha particle will be

1. $1MeV$
2. $4MeV$
3. $0.5MeV$
4. $1.5MeV$

Q.

A metallic square loop ABCD is moving in its own plane with velocity v in a uniform magnetic field perpendicular to its plane as shown in Fig. 25.25. An electric field is induced

1. in AD, but not in BC

2. in BC, but not in AD

3. neither in AD nor in BC

4. in both AD and BC

Q.

A metallic square loop ABCD is moving in its own plane with velocity v in a uniform magnetic field perpendicular to its plane as shown in Fig. 25.25. An electric field is induced

1. in AD, but not in BC

2. in BC, but not in AD

3. neither in AD nor in BC

4. in both AD and BC

Q. Two coils A and B having turns 300 and 600 respectively are placed near each other, on passing a current of 3.0 ampere in A, the flux linked with A is 1.2 x 10 −4 weber and with B it is 9.0 x 10 −5 weber. The mutual induction of the system is:

Q. The monoenergetic beam of electrons moving along + y direction enters a region of uniform electric and magnetic fields. If the beam goes straight undeflected, then fields B and E are directed respectively along

1. -y axis and - z axis
2. + z axis and + x axis
3. + x axis and + z axis
4. - x axis and - y axis

Q. A charge $+q$ moves parallel to a very long straight wire carrying a current $I$ as shown. The force on the charge is

1. opposite to $oy$
2. opposite to $ox$
3. along $ox$
4. along $oy$

Q. A charged particle (charge $q$, mass $m$) has velocity $v_0$ at the origin in +x direction. In space, there is a uniform magnetic field B in –z direction. Find the y coordinate of the particle when it crosses y axis.

1. $\frac{2m{v}_0}{qB}$
2. $\frac{m{v}_0}{qB}$
3. $\frac{4m{v}_0}{qB}$
4. None of these

Q. Angular velocity of a particle moving in a straight line is