Drift Velocity

Q.

Define the term ‘mobility’ of charge carriers. Write its S.I. unit

Q.

The mobility of charge carriers increases with

1. Increase in the average collision time

2. Increase in the electric field

3. Increase in the mass of the charge carriers

4. Decrease in the charge of the mobile carriers

Q.

Define the relaxation time of the free electrons drifting in a conductor. How is it related to the drift velocity of free electrons? Use this relation to deduce the expression for the electrical resistivity of the material.

Q. 21. Two large conducting plates are placed parallel to each other with a separation of 2.00 cm between them. An electron starting from rest near one of the plates reaches the other plate in 2.00 microseconds. Find the surfacecharge density on the inner surfaces.

Q. Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area $1.0\times {10}^{-7}{m}^2$carrying a current of $1.5A$. Assume the density of conduction electrons to be $9\times {10}^{28}{m}^{-3}$.

Q.

Define mobility of a charge carrier. What is its relation with relaxation time?

Q. For which of the following dependence of drift velocity $V_d$ on electric field $E$ is Ohm's law obeyed ?

​​​​​​​$[$1 Mark$]$

1. $V_d\propto E$
2. $V_d$ = Constant
3. $V_d\propto \sqrt{E}$
4. $V_d\propto E^2$

Q. Two identical charges each having $Q$ are fixed at a distance $2d$ apart. A third particle having a mass $m$ and charge$-q$ is projected from the midpoint of the line joining the two charges along a direction perpendicular to the line joining the two charges. Find the minimum velocity to be imparted, such that $-q$ charge reaches infinity.

1. $\sqrt{\frac{KQq}{md}}$

2. $2\sqrt{\frac{KQq}{md}}$

3. $\sqrt{\frac{KQq}{2md}}$

4. $\frac{1}{2}\sqrt{\frac{KQq}{md}}$

Q.

Uniform electric field of 10NC^-1 exist in the vertically downward direction find the increase is electric potential as one goes up through a height of 50 cm

Q.

The distance traveled $s$ (in metres) by a particle in $t$ seconds is given by $s=t^3+2t^2+1$. The speed of the particle after $1second$ will be

1. $8cm/sec$

2. $6cm/sec`$

3. $2cm/sec$

4. None of these

Q.

What does Lambda mean in electric field?

Q.

A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along the length of the conductor is/are

1. Current only.

2. Current, electric field and drift velocity

3. Current and drift speed

4. Speed only

Q.

What is the difference between gauss theorem and gauss law ?

Q. A current flows in a wire of circular cross-section with the free electrons travelling with a mean drift velocity v. If an equal current flows in a wire of twice the radius, then the new mean drift velocity is

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

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.

The positive mutual potential energy of a system containing two charges corresponds to

Q.

A current of $3.2A$ is flowing through a conductor. The number of electrons flowing per second is

1. $51.2\times {10}^{19}$

2. $5.12\times {10}^{24}$

3. $3.2\times {10}^{19}$

4. $2\times {10}^{19}$

Q. Charge passes through a conductor of cross section at area $A=0.3m^2$ is given by $q=3t^2+5t+2$ in coloumb, where t is in second. What is the value of drift velocity at t = 2 sec (given n = $2\times {10}^{25}/m^2$)?

1. $0.77\times {10}^{-5}m/s$
2. $1.77\times {10}^{-5}m/s$
3. $2.08\times {10}^{-5}m/s$
4. $0.57\times {10}^{-5}m/s$

Q. A proton, a deutron and an $\alpha$-particle having the same momentum, enters a region of uniform electric field between the parallel plates of a capacitor. The electric field is perpendicular to the initial path of the particles. Then the ratio of deflections suffered by them is

1. None of these
2. 1 : 2 : 8
3. 1 : 2 : 4
4. 1 : 1 : 2

Q. The force on electrons due to the electric field set up inside a conductor, doesn’t accelerate them on an average because

1. Newton’s second law is not valid inside a conductor
2. Some mysterious force pulls the electrons in the other direction
3. The electrons keep hitting the fixed positive ions and lose their momentum
4. Electrical force can never accelerate a charge

Q. Define the term 'mobility' of charge carries in a conductor . Write its SI unit .

Q. Define mobility. Give its unit.

Q.

A copper wire of mass $20g$ carries a current of $6.023A$. What fraction of the total number of free electrons present in the copper wire flows through the cross-section of the copper wire in $2sec$? (gram atomic weight of copper is $63.5g$).

Q. Define mobility of a charge carrier. What is its relation with relaxation time?

Q. The drift velocity of free electrons through a conducting wire of radius r, carrying current I, is v_{​​​​​​d}. If the same current is passed through a conductor of radius 2r. What will be the drift velocity?

Q.

What is electrical discharge and what is electrical breakdown

Q. Drift speed of electron, when 1.5 A of current flows in a copper wire of cross section $5m{m}^{2}isv$. If the electron density in copper $9\times {10}^{28}/m^3$ the value of $vinmm/s$ is close to (Take charge of electron to be $=1.6\times {10}^{-19}C$)

1. 2
2. 0.2
3. 0.02
4. 3

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.

Can I have cbse board preparation notes of chapter ""electric potential and capacitance"" of physics... Please give me detailed notes....

Q. A uniform metal rod is moving with a uniform velocity V parallel to the long straight wire carrying a current I . The rod is perpendicular to the wire with its end at distance R1 and R2 ( with R2 > R1 ) from it .The EMF induced in the rod is