This document discusses electrical power and energy. It defines electrical power as work done per unit time (P=W/t) and gives the formulas for power as P=VI and P=I^2R. It defines 1 watt as 1 amp of current flowing through a circuit at 1 volt. It also defines the kilowatt-hour (kWh) as the energy consumed by a 1 kilowatt device over 1 hour, which equals 36,000 joules or 1 unit. Some numerical examples are provided to calculate power using the given formulas and units. Electrical energy is defined as power multiplied by time using the formulas E=P*t, E=VIt, and E=V^2/R
2. 1
IN CLASS 9
Electric POWER is defined as Work Done per unit Time
P= W/ t
In Electricity Electric Power = Work / time
As V= W/ q , So W = V X
q
Electric Power = V x q
t
As I = q/ t Electric Power = V x I
P = V I
Quantum SOLUTIONS
6. 4
DEFINE 1 WATT?
Quantum SOLUTIONS
The power of an electrical appliance is said to
be 1 watt if 1 amp of current flow through it
when connected to 1 volt of potential diff.
P = VI
7. 5
ANOTHER FORMULE OF ELECTRIC POWER
AS I = V/R
AS V=IR
P= V2/R
ELECTRIC
POWER
P = V I
P= I2R
Quantum SOLUTIONS
9. 7
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NUMERICAL 1
NO??
YES??
If the current and voltage of an electric circuit are given as
2.5A and 10V respectively. Calculate the electrical power?
PROBLEM
SOLVING Confusions?
Quantum SOLUTIONS
GIVEN
I = 2.5A
V = 10V
THE FORMULA FOR ELECTRIC POWER IS,
P = VI
P = 10 × 2.5 = 25WATTS
10. 7
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NUMERICAL 2
NO??
YES??
Calculate the power of an electrical circuit consisting of
resistance 3Ω and a current 4A flowing through this circuit?
PROBLEM
SOLVING Confusions?
Quantum SOLUTIONS
GIVEN
I = 4A
R = 3Ω
ELECTRIC POWER FORMULA IS,
P = I2R
P = 42×3
P = 16×3 = 48 WATTS
16. 4
DEFINE 1 KILOWATT-HOUR (KW-H)?
Quantum SOLUTIONS
The energy consumed by a device of POWER
rating 1 kilowatt when used for 1 HOUR, is
known as 1 Kilowatt-hour.
E = P X T
1 KW-H = 36,00,000 JOULES
1 KW-H = 1 UNIT
17. DEFINE COMMERCIAL UNIT OF ELECTRICAL ENER
OR
DEFINE 1 KW-H.
THE AMOUNT OF ENERGY USED BY AN ELECTRICAL APPLIANCE OF
POWER RATING 1KW, WHEN USED FOR 1HOUR, IS KNOWN AS 1 KW-HR.
12345675
Gyser
12345685
19. 3
ELECTRIC ENERGY
Quantum SOLUTIONS
A POWER STATION OF MEGAWATT OF CAPACITY WILL
PRODUCE ELECTRICITY THAT EQUATES TO ABOUT THE SAME
AMOUNT OF ELECTRICITY CONSUMED BY 400 TO 900 HOMES IN A
YEAR.
MEGAWATT
1 MW = 1000 WATTS