Drift Velocity

Q. Thermal velocity of electron is 10^5. But average velocity is zero why

Q. A cannon fires a shell with a speed of 84 m s−1. When the cannon is inclined at 45°, the horizontal distance covered is observed as 630 m. What is the percentage decrease in the horizontal distance observed due to a resistance?

Q. The current through two inductors of self inductance 12 mH and 30 mH is increasing with time at the same rate. Draw graphs and Compare the energy stored in the coils if power dissipated in the coil is same.

Q. Kinetic energy is also a periodic function of time, being zero when the displacement is maximum and minimum when the particle is at the mean position. explain the statement

Q. A current $I$ flows through a flat metal specimen of constant thickness and of the shape as shown in the figure. Given that $v_1,v_2$ and $v_3$ are mean drift speeds of the electron crossing the sections $P_1,P_2$ and $P_3$ respectively. Then

1. $v_2<v_1<v_3$
2. $v_1<v_2<v_3$
3. $v_1=v_3<v_2$
4. $v_1>v_2=v_3$

Q. A beam of electrons is moving with constant velocity in a region having electric and magnetic fields of strength $20{\text{Vm}}^{-1}$ and $0.5\text{T}$ at right angles to the direction of motion of the electrons. What is the velocity of the electrons ?

Q. The average time of motion of electrons between two successive collisions with fixed positive ions inside a conductor is called the ___ time

1. active
2. relaxation
3. collision time
4. none of these

Q. When a current $I$ is set up in a wire of radius $r$, the drift velocity is $v_d$. If the same current is set up through a wire of radius $2r$ of same material, the drift velocity will be

1. $4v_d$
2. $\frac{v_d}{2}$
3. $2v_d$
4. $\frac{v_d}{4}$

Q. { Time period of a particle executing }SHM is }8 second. At }t=0 it is at the mean position. The ratio of distance }}{ covered by the particle in the }1^ st } second to the }2^ nd } second

Q. A current $I$ flows through a flat metal specimen of constant thickness and of the shape as shown in the figure. Given that $v_1,v_2$ and $v_3$ are mean drift speeds of the electron crossing the sections $P_1,P_2$ and $P_3$ respectively. Then

1. $v_2<v_1<v_3$
2. $v_1<v_2<v_3$
3. $v_1=v_3<v_2$
4. $v_1>v_2=v_3$

Q. A wire has poisson ratio is .3 .if thr change in the length of the wire on stretching it is 1% thennpercentage change in volume of the wire is

Q. Thermal velocity of electron is 10^5. But average velocity is zero why

Q. In a conductor, electrons drift from lower to higher potential. If drift speed is $V_d$ and speed due to random motion (due to temperature) is $V_r$, then net velocity of electron can be.

1. $V_d+V_r$
2. $V_r-V_d$
3. $\sqrt{V_d^2+V_r^2}$
4. All of the above

Q. A current I is passing through a wire having two sections P and Q of uniform diameters d and $\frac{d}{2}$ respectively. If the mean drift velocity of electrons in sections P and Q is denoted by $v_p$and $v_Q$respectively, then

1. $V_p=V_Q$
2. $V_p=\frac{1}{2}{V}_Q$
3. $V_p=\frac{1}{4}{V}_Q$
4. $V_p=2V_Q$

Q. A current I is passing through a wire having two sections P and Q of uniform diameters d and $\frac{d}{2}$ respectively. If the mean drift velocity of electrons in sections P and Q is denoted by $v_p$and $v_Q$respectively, then

1. $V_p=V_Q$
2. $V_p=\frac{1}{2}{V}_Q$
3. $V_p=\frac{1}{4}{V}_Q$
4. $V_p=2V_Q$

Q.

The electric field maintained inside a conductor is 10N/C and they drift with a speed of $5\times {10}^{-4}m/s$
What is the relaxation time for the electrons?

1. $\frac{5m}{e}\times {10}^{-5}$ seconds where m is the mass of the electrons and e is the charge

2. $\frac{5e}{m}\times {10}^{-5}$ seconds where m is the mass of the electrons and e is the charge

3. $\frac{m}{e}\times {10}^{-4}$ seconds where m is the mass of the electrons and e is the charge

4. $\frac{5m}{e}\times {10}^{-4}$ seconds where m is the mass of the electrons and e is the charge