Current and Drift Velocity

Q.

How many electrons are there in 1 Ampere of current?

Q.

Why 1 coulomb is 6.25*10^18 electrons ?

Q. If the charge of an electron is 1.6*10^-19 coulombs, how many electrons should pass through a conductor in 1 second to constitute 1 ampere current?

Q. An electric iron draws current of 0.5A when voltage is 200V. Calculate amount of charge.

Q. How coagulation power and gold number are related?

Q. A body has a negative charge of 2 micro coulomb. If body has 2.25*10^12 protons , then number of elctrons present in the body will be

Q.

In 10 second a charge of 25 c leaves a battery and 200j of energy are delivered to outside circuit as a result, what is potencial difference across battery and what current flows from battery.

Q.

Why bulb glows immediately since drift speed of electrons is 10^-4 m/s

Q.

10A OF CURRENT PASSING THROUGH A CONDUCTOR IN MIN. FIND NUMBER OF ELECRON CROSSING THROUGH THE CONDUCTOR.

Q. What is the value of the charge of an electron?

1. 9 × 10^-38 Coulomb
2. 6.62 × 10³² Coulomb
3. 1.6 × 10^-19 Coulomb
4. 1.6 × 10¹⁹ Coulomb

Q.

A glass rod rubbed with silk and was found to have +5 micro coulomb of charge .how many electrons got transferred and from which material?

Is the answer is 3.123*10^13 electrons..

Q. If a charge of an electron is 1.6×10^-19 coloumb , how many electrons should pass through a conductor in 1second to constitute 1 ampere current?

Q.

How many electrons flow through an electric bulb every second of the current that passes through it is 2 ampere

Q. If one billion electrons travel through a conductor in one nano second , how many micro amperes of current are flowing through it?

Q. The area of cross section of a conductor is $10c{m}^2$ and a current of $3A$ is flowing through it. The drift velocity of electrons is $4\times {10}^{-4}m{s}^{-1}$. What will be the new cross sectional area if we are increasing the drift velocity to $7\times {10}^{-3}m{s}^{-1}$ keeping the current flow constant?

1. $0.5714c{m}^2$
2. $0.3931c{m}^2$
3. $0.4032c{m}^2$
4. $0.6618c{m}^2$

Q. The number of electrons present in 8 coulomb of charge

Q. Number of electrons in a conductor of area of cross section $0.4m^2$ is ${10}^{23}{m}^{-3}$. If the drift velocity of the electrons is $4\times {10}^{-5}m{s}^{-1}$, what is the current flowing through the conductor in ampere? (Take electron charge as $1.6\times {10}^{-19}C$)

1. 0.256

Q. The drift velocity of free electrons in a conductor is $v$, when a current. $I$ is flowing in it if both the radius and current are doubled, then drift velocity will be.

1. $v/4$
2. $v/2$
3. $2v$
4. $4v$

Q. Ram knows that relation between current and drift velocity is $I=neA{V}_d$_.He is trying to solve a question where the current in a cylindrical conductor is to be calculated. The total number of electrons In the conductor is given as ${10}^{26}$, their drift speed is ${10}^{-2}cm/s$ and the cross- sectional area is $1m^2$ uniform throughout the conductor and its length is given as 2m
He writes this equation $I=neA{V}_d$
$={10}^{26}\times 1.6\times {10}^{-19}\times 1\times \frac{{10}^{-2}}{100}$
He gets a terribly wrong answer.
This is because

1. Ram is not using the correct value of the charge of an electron
2. Ram converted the units of speed into SI units wrongly
3. Ram doesn’t know that n stands for number of electrons per unit volume and not total number of electrons.
4. None of the above! Ram must have done some calculation mistake.

Q. A steady current flows in a metallic conductor of non uniform cross-section. The quantity that remains constant along the length of the conductor is

1. drift speed only
2. current, electric field and drift speed
3. current and drift speed
4. current only

Q. A current of $0.43A$ is flowing through a wire of thickness $2cm$. If there are ${10}^{18}$ electrons per $c{m}^3$ of the wire, calculate the drift velocity of electrons in $m{s}^{-1}$. Take the electron charge as $1.6\times {10}^{-19}C$.

1. $4.277\times {10}^{-3}m{s}^{-1}$
2. $8.554\times {10}^{-3}m{s}^{-1}$
3. $1.283\times {10}^{-4}m{s}^{-1}$
4. $3.697\times {10}^{-3}m{s}^{-1}$

Q.

If 10²⁰ electrons flow from the black body to the Gray body through a copper wire in 8 seconds, what is the amount of current flowing in the copper wire in that time interval ?

Q.

which physical quantity does electron volt measure ? How it is related to si unit of quantity?

Q.

The SI unit of electric power is ___________.

Q. A conductor has an area of cross section $S$. If the electron charge is '$e$' and the drift velocity of '$m$' number of free electrons is '$v_D$', then the ratio of $v_D$ to the current $i$ flowing through the conductor is given by:

1. $Sem$
2. $(Sem{)}^{-1}$
3. $Sm{e}^{-1}$
4. $Se{m}^{-1}$

Q.

In which of the following case, the flow of electric current will be maximum?

1. When the potential difference across the device is more

2. When the potential difference across the device is less

3. When resistance of the material used is high

4. When there is no potential difference

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 and drift speed
2. Current only
3. Current, electric field and drift speed
4. Drift speed only

Q.

How is it so that a bulb glows as soon as it's switch on; though the electron drift Wat the speed of 1 or 2 cm/ s

Q. An electric field is applied to a semiconductor. Let the number of charge carriers be $n$ and the average drift speed be $v$. If the temperature is increased,

1. both $n$ and $v$ will increase
2. $n$ will increase but $v$ will decrease
3. $v$ will increase but $n$ will decrease
4. both $n$ and $v$ will decrease

Q.

A glass rod is rubbed with silk and was to found to have 5micro coulomb of charge. How many electrons got transfered and from which material