Electric power is the rate at which electrical energy is transferred by an electric circuit per unit of time. The watt, or one joule per second, is the SI unit of power. Electric generators are the most common source of electricity, but other sources such as electric batteries can also be used.
The coulomb (C) is the SI unit of electric charge, and it is equal to the charge contained in almost 6 10 18 electrons. (An electron has a negative charge of 1.6 10–19 C, as we know.) The ampere (A) is a unit of electric current named after the French scientist Andre-Marie Ampere (1775–1836). The flow of one coulomb of charge per second, or 1 A = 1 C/1 s, is equal to one ampere. Microampere (1 A = 10–6 A) and milliampere (1 mA = 10–3 A) are used to measure small amounts of current. An ammeter is a device that measures electric current in a circuit. In a circuit when the current is to be measured, it is always linked in series.
What is electric power? Derive 
, where 
is the amount of heat produced by steady curnent I through a resistor 
in time t.
, where is the amount of heat produced by steady curnent I through a resistor in time t.What is electric power? Derive , where is the amount of heat produced by steady curnent I through a resistor in time t.
, where is the amount of heat produced by steady curnent I through a resistor in time t.
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west of the geographic north. The north tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points above the horizontal. The horizontal component of the earth’s field is measured to be 
Specify the direction and magnitude of the earth’s field at the location.At a certain location in Africa, a compass points 
and 
carrying currents of 
and 
in the same direction are separated by a distance of 
. Estimate the force on a 
section of wire A.
wire carrying a current of 
is placed inside a solenoid perpendicular to its axis. The magnetic field inside the solenoid is given to be 
. What is the magnetic force on the wire?
and making an angle of 
with the direction of a uniform magnetic field of 
. What is the magnitude of the field 
at a point 
from the wire?
-turns carrying current 
.
is at distance 
from the wire. Find the force acting on the electron if its velocity is directed towards the wire.