Question

anyone who tell me the all formulas of 2nd year 13 chapter physics plzzzz i mark it as brilliant?

Answer 1

Q # 1. What do you know about electric current?

Ans. Electric Current

The amount of electric charge that flows through a cross section of a conductor per unit time is known as electric current.
If is the amount of charge flow through a cross-section in time , then the electric current is described mathematically as:
It is a base quantity and its unit is ampere.
Ampere
If one coulomb charge flows through a cross-section of a conductor in one second then the current will be one ampere.
Q # 2. Write down a note on the direction of flow of current through any conductor.
Ans. Current direction
Earlier, it was thought that the current flow through a conductor due to positive charges from higher potential to lower potential in any external circuit. But later on, it was found that the flow of current in metallic conductor is due to the flow of electrons from the point of lower potential to the point of higher potential.
But still we also take the direction of flow of current along the flow of positive charges. The reason is that it has been found experimentally that positive charge moving in one direction is equivalent in all external effects to a negative charge moving in opposite direction.
Conventional current
The current flow due to positive charges from a point at higher potential to a point at lower potential is called conventional current.
Q # 3. Describe the effect of electric field on the motion of free electrons.
Ans. All atoms contain free electrons. In the absence of any external electric field, the free electrons are in random motion just like the molecules of gas in a container and the net current through wire is zero.
If the ends of the wire are connected to a battery, an electric field (E) will setup at every point with in the wire. Due to electric effect of the battery the electrons will experience a force in the direction opposite to E.


Drift velocity
When electric field is established across the ends of a conductor, the free electrons modify their random motion and drift slowly with a constant velocity in the direction opposite to E. This constant velocity is known as drift velocity.
Q # 4. Write down a note on the sources of current?
Ans. Sources of current
A source which maintains constant potential difference between the ends of the conductor is called sources of current. Source of current converts some non electrical energy (chemical, mechanical, heat or solar energy) to electrical energy.
Examples
i) Cells which convert chemical energy into electrical energy.
ii) Electric generators convert mechanical energy into electrical energy.
iii) Thermo couples convert heat energy into electrical energy.
iv) Solar cells convert light energy into electrical energy.
Q # 5. Describe the effects of current?
Ans. Effects of Current.
The presence of current produces various effects through which it can be detected. Its some effects are given below
i) Heating effect.
ii) Magnetic effect.
iii) Chemical effect.
i) Heating Effect
Current flow through a metallic conductor due to the motion of free electrons. During their motion they frequently collide with one another. On each collision they transfer some of their kinetic energy to the atom with which they collide. And these collisions produce heating effect in the wire.
It is found that the heat H produced by the current I in the wire of resistance R during time interval y is given by the expression:
The heating effect of the current is utilized in electric heaters, kettle, toaster and electric iron etc.
ii) Magnetic Effect
The flow of current always carries magnetic field surrounding it in space. The strength of magnetic field depends upon the value of current and the distance from the element. The pattern of the field produced by a current carrying straight