Question
Electrons are continuously in motion within a conductor but there is no current in it unless some source of potential is applied across its ends. Give reason.
✓
Answer
In the absence of any external source the motion of electrons in a conductor is random and electrons collide continuously with the positive ions of metal. This causes a random change in direction of motion. The average velocity of random motion of electrons in any direction is zero, hence current is zero.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
If a piece of paper is placed at the position of a virtual image of a strong light source, will the paper burn after sufficient time? What happens if the image is real? What happens if the image is real but the source is virtual?
The number of silicon atoms per $m^3$ is $5 \times 10^{28}$. This is doped simultaneously with $5 \times 10^{22}$ atoms per $m^3$ of Arsenci and $5 \times 10^{20}$ per $m^3$ atoms of Indium. Calculate the number of electrons and holes Given that $n_i = 1.5 \times 10^{16} m^{-3}$. Is the material $n-$ type or $p-$ type?
→Consider a two slit interference arrangements such that the distance of the screen from the slits is half the distance between the slits.
Obtain the value of D in terms of $\lambda$ such that the first minima on the screen fall at a distance D from the centre O.
Is the colour of 620nm light and 780nm light same? Is the colour of 620nm light and 621nm light same? How many colours are there in white light?
The magnetic field $B$ inside a long solenoid, carrying a current of $5.00A,$ is $3.14 \times 10^{-2}T.$ Find the number of turns per unit length of the solenoid.
→Figure shows a metallic square frame of edge a in a vertical plane. A uniform magnetic field B exists in the space in a direction perpendicular to the plane of the figure. Two boys pull the opposite corners of the square to deform it into a rhombus. They start pulling the corners at t = 0 and displace the corners at a uniform speed u.
- Find the induced emf in the frame at the instant when the angles at these corners reduce to 60°.
- Find the induced current in the frame at this instant if the total resistance of the frame is R.
- Find the total charge which flows through a side of the frame by the time the square is deformed into a straight line.
What is the shape of the wavefront in each of the following cases:
(a) Light diverging from point source.
(b) Light emerging out of a convex lens when a point source is placed at its focus.
(b) (c) The portion of the wavelength of light from a distant star intercepted by the Earth.
(a) Light diverging from point source.
(b) Light emerging out of a convex lens when a point source is placed at its focus.
(b) (c) The portion of the wavelength of light from a distant star intercepted by the Earth.
Find the charges on the three capacitors connected to a battery as shown in figure. Take $\text{C}_1=2.0\mu\text{F},\ \text{C}_2=4.0\mu\text{F},\ \text{C}_3=6.0\mu\text{F}$ and V = 12 volts.
→A person standing on a platform finds that a train moving with velocity 0.6c takes one second to pass by him. Find:
- The length of the train as seen by the person and.
- The rest length of the train.
What is called extrinsic semiconductor? Explain doping process.