CBSE CLASS X ELECTRICITY

1. ELECTRICITY
Chapter 12

2. Electricity
Electric
Current
Electric
Potential
Heating
Effect of
Electric
Current
Ohm’s
Law

3. ELECTRIC CURRENT
DEFINITION : THE RATE OF FLOW OF CHARGE IS CALLED CURRENT
I =Q/t
= Charge/Time
X Y

5. ELECTRIC CURRENT
 electric current was considered to be the flow of positive
charges
 The direction of flow of positive charges was taken to be the
direction of electric current.
 Conventionally, in an electric circuit the direction of electric
current is taken as opposite to the direction of the flow of
electrons, which are negative charges.
X
Y

6.  If a net charge Q, flows across any cross-section of a
conductor in time t, then the current I, through the cross-
section is
I =Q/t --(1)
= Coulomb/second
= C/S
 The SI unit of electric charge is coulomb (C)
 The electric current is expressed by a unit called ampere (A)
 One ampere is constituted by the flow of one coulomb of
charge per second, that is,
 1 A = 1 C/1 s.

7. AMPERE METER

8. ELECTRIC CIRCUIT
electric circuit comprising a cell, an electric bulb, an ammeter and a plug key.

9. Q. A current of 0.5 A is drawn by a filament of an electric bulb for 10
minutes. Find the amount of electric charge that flows through the
circuit.
Solution
We are given,
I = 0.5 A
t = 10 min
= 10 * 60 s
= 600 s.
From Eq. (1), we have
Q= It
=0.5 A × 600 s
=300 C

10. Answer the following Questions:
1. What does an electric circuit mean?
2. Define the unit of current.
3. Calculate the number of electrons constituting one coulomb of
charge.

11. Thank You